Part I `I don't understand why you always want to stick things in my ass', Nina repeated her all-time favorite complaint. We just returned from a Sunday afternoon shopping trip. It was quite windy outside. All through the afternoon her short skirt kept flying and exposing her thongs. Nina has an awesome looking ass. I saw guys at the shopping center stare and smile every time the wind exposed it. When we finally got home, I was very horny. I lifted the back of her skirt and started massaging her butt. Nina loves afternoon sex. She says it turns her on when it's sudden and unplanned. Things heated up a bit and Nina started wiggling her ass against my massaging hands. A few minutes later I tried sticking a finger in Nina's asshole. Nina doesn't like anal sex, and I knew she wasn't going to like my last move. I simply couldn't stop myself. `I can't even begin to explain how much fun your asshole is' I said. It wasn't the first time I used this argument and I knew it would fail. `Why do you always want my asshole', Nina said `I have a few other nice body parts for you to obsess with, don't I?'. `Of course you do. I love all your body parts.' I said. I lost this argument many times before. Suddenly I had an idea. Our shopping included a lot of fruits, and one of them was a large watermelon. I looked at the watermelon, and decided to try a new approach. `Actually, maybe I CAN explain', I said. `See, your ass is very smooth and very round. Just like this watermelon.'. `Are you trying to say that my ass is too big?' Nina asked angrily. `No, No, Let me explain, you'll see in a second'. I took a sharp knife from the kitchen counter and started carving the watermelon. I carved a crack along the side of the watermelon - deep enough to expose the red watermelon meat but but deep enough to cut it in two. `Your ass is a lot more tempting than this watermelon but it would just have to do. Slide your hand over the watermelon surface and feel how smooth it is. Your ass is even nicer because it is both round and soft.'. Nina was reluctant to participate in my experiment but eventually she started rubbing the smooth surface of the watermelon. `OK. I get it. It's smooth. I don't understand what this has to do with anal sex' Nina said. I took the knife and carved a tiny hole in the middle of the watermelon crack. `Now, feel the new hole I made' I said. Nina slid her hand into the red crack and moved it around the hole. `I don't get it. It's just a watermelon' she said. `Yes, it's just a watermelon. Now use your index finger and push it into the hole' I said. `When you feel the watermelon meat resist your finger, push harder'. Nina stuck her index finger forward and slowly pushed it into the watermelon. The red watermelon meat objected her finger at first but caved-in and let her finger plunge in as her pressure increased. Red watermelon juice started pouring down from the red hole into the counter top. `When your finger is all the way in, start wiggling it', I said. Nina was silent. I saw her finger sink into the watermelon as deep as it could. I looked at her face and saw she was blushing. `This is embarrassing', she giggled. `I am actually enjoying this'. More and more watermelon juice accumulated on the counter top. I went to get a paper towel in order to clean the mess. When I returned, she had two fingers stuck in the watermelon. I saw her hand moving as her fingers wiggled inside the watermelon. `Damn, I am horny' she said. I saw her trying to squeeze more fingers into the watermelon. The entire counter top was no covered with red watermelon juice. Nina's ass was moving back and forth as her fingers were fucking the watermelon. I decided it was a good time to try Nina's ass. I took some hand lotion and started rubbing it on Nina's ass. She responded by thrusting her butt against my hand, making funny sounds. I looked at her fingers but couldn't see any. her entire hand was buried inside the watermelon, crushing its red meat from the inside. Red juice was now pouring on the floor. I pushed my index finger against her asshole. This time she didn't object. She made low moaning sounds as her second hand tried to squeeze into the watermelon crack. I slid a second finger into her asshole and started finger fucking her. Her butt responded by wiggling around my fingers and she spread her feet farther on the floor. She was in some kind of a trance, her hands smashing the inside of the watermelon. Without a warning, I took my fingers out of her asshole and plunged my dick right in. Her asshole was already lubricated so my dick dived in all the way immediately. Her ass began moving back and forth - meeting my thrusts. I was so horny that I came inside her asshole in just a few minutes. Can you blame me? I was very excited. It was the first time Nina let me fuck her asshole. I collapsed on the kitchen floor enjoying the sensation. I didn't pay much attention to Nina. Her hands kept fucking that watermelon. There wasn't much meat left in it. A minute or two later, Nina stopped. She took her hands out of the watermelon and washed them. She then turned to me and asked: `Does my ass really feel like the inside of a watermelon?'. `It's a million times better', I answered. `A watermelon doesn't contract when you remove your finger. Fucking a watermelon, you only get that penetration feeling once. It doesn't put any pressure on your fingers after the first thrust'. Nina's eyes were looking at the floor. She was blushing again. `What is it?' I asked. Nina wouldn't answer. I never imagined convincing her to have anal sex could be so simple. I was still overwhelmed with my orgasm. Nina's eyes wouldn't meet mine. `What happened?' I asked again. `I ... hmm ... I'm too embarrassed' she said. `Come on, don't be scared, tell me'. Nina raised her eyes, met my eyes and then dropped her gaze to the floor. `I want to do you too' she whispered. `Do what?' I asked, confused. `I want to try fucking your ass too' she said. Her face was completely red. `What do you mean?' I protested. `I am a guy. Girls don't finger-fuck a guy's ass. It's not normal'. `Well, You made me try it and I liked it. Now I want the real thing', Nina said, her eyes still staring at the floor. Part II I was very busy at work through the next week. I had to prepare a meeting with an important customer and ended up spending the weekend at work too. Nina spent most of these evenings by herself. Late every night, when I finally arrived home, I found Nina surfing the Internet. She doesn't usually spend this much time over the Internet. I figured she was bored with Television. I still remembered what Nina said after our watermelon incident, but I didn't have enough time to think about it. My birthday was only a few weeks away. We didn't spend a lot of time together through the past weeks so I made sure to be home early on my birthday. Nina opened the door wearing nothing but an apron. It wasn't the first time she does that but it gets me every time. There's something very sexy about an apron ... I tried to hug her and grab her ass but she wouldn't let me. She said I had to eat first before I get my dessert. Nina cooked a terrific meal and we indulged on it together. When we finished eating, Nina took my hand and led me to our bedroom. I could see that she was a little stressed. `What happened?' I asked. `I have a surprise for you', Nina answered. `You'd have to keep a very open mind, OK?'. I didn't know what it meant, but her outfit was so sexy that I stopped using my brain and I let my dick take over. Nina made me stand with my legs spread a little. She took my clothes off and left me standing completely naked. She then stood on her knees in front of my dick and took it in her mouth. Nina gives the best possible blow-jobs. She knows how to drive me insane with her tongue motion. She was going very slow, warming me up. I was very happy and forgot all about the `very open mind' part. At some point, Nina took my dick out of her mouth, and said: `Very open mind. Remember?'. I was having so much fun that I didn't really hear what she said. She started rubbing my balls. This wasn't anything new either. I liked her light touch on my balls. Suddenly, one of her hands slid between my legs and started stroking my ass cheeks. Then, her other hand slid between my legs and joined the first one. I remember Nina stroking my ass cheeks while sucking me before but it wasn't very common. Nina took my dick out of her mouth again and said: `Trust me'. She kept on sucking on my dick and her hands left my ass. A few seconds later, I felt something wet on my ass cheeks. Her hands were stroking me again, this time with something very oily. She started rubbing my ass cheeks and smearing some oily stuff all around my ass cheeks. Nina never gave me an ass massage before. It felt very nice. I sank back into the a relaxed mode - half closing my eyes, my dick getting the best possible blow-job and my ass getting a light massage. Nina took my dick out of her mouth again and asked: `Promise to let me finish what I'm doing without saying a word'. I was so relaxed and pleased with myself that I just said: `of course'. I guess I said what she wanted to hear. She went back to sucking my dick, and her hands went back to rubbing my ass. Her rubbing motion started covering more and more of my ass cheeks. Suddenly I realized that she was almost touching my asshole. I finally clicked - our watermelon experiment. Damn. How did I miss that. Nina's hands were now moving in circles around my asshole. The palms of her hands started rubbing against my asshole. She must have been excited about this because her sucking became harder and more demanding. As long as nothing went inside my asshole, I was OK with the hard massage. Nina's made eye contact with me, and then I felt her finger push in. My immediate reaction was to tighten my ass muscles. She must have expected this. She withdrew her hands, got more of the oily lotion and returned to massaging my asshole with the palms of her hands. Every few seconds, she tried to stick her finger in. Every time, I contracted my ass muscles and she removed her finger. Each time, Nina would stick her finger just a bit deeper that the previous time. A few minutes went by and Nina's finger now penetrated about an inch into my asshole. Suddenly, her finger went past my asshole muscle and dived all the way in. It was a very strange feeling. Not a good feeling, but also not a painful one. I looked down at Nina's eyes. She looked very pleased with herself - pleased in a very sinful way. I was completely surprised at what happened less than 10 seconds later. Nina wiggled her finger in my ass and without a warning I felt a huge orgasm build in my balls. I had absolutely no control over it. It felt different than my normal orgasms. It started much deeper in my body. Nina didn't expect such a quick reaction. She was still sucking my dick at her regular pace when it exploded in her mouth, squirting more and more cum. Nina can usually take my cum. This time it was too sudden and she gagged on it. Some of the cum spilled out of the corner of her mouth and dripped onto her cheek. She recovered quickly and swallowed the rest, looking into my eyes as she did. My body was twitching for a while, trying to contain the orgasm. When it finally relaxed, I looked down at Nina. She was smiling at me, kissing the tip of my dick. `Did you like it?' she asked. `Yeh ... What were you doing there?' I answered. She smiled at me mysteriously for a few seconds and then said: `I found your G-spot'. `I don't have a G-Spot. I'm a guy' I said, a bit confused. `OK, I found your prostate. It's the same thing', she said. `I didn't expect such a quick reaction. On the web it said I had to curl my finger towards your dick, find a hard surface and press hard. That web-page didn't say how fast it would be ... Maybe I pressed too hard ...'. We were both silent for a few minutes. Me, trying to understand what exactly happened, and Nina, pleased with her work. `I'm very horny now', Nina said finally. `I didn't fuck your asshole quite the way I wanted to. I wanted this to be your gift. Not mine. Is your dick ready for some more?'. `I'm afraid I'm completely deflated for a little while.', I answered. `Will you help me get off?' she asked in a shy voice. I waited for that question. My tongue was ready for Nina's clit, and my fingers were so ready for her asshole ...