Katie was 14 and I was 12. We had just moved back with 
our mother and were staying with her and her current 
boyfriend Mark. They had a one bedroom apartment together 
and were not quite prepared to host my sister and I at 
the time we arrived to live with them.

Let me start by saying that my sister and I have always 
been very close. The products of a divorced household at 
an early age; we were forced to grow up quickly. We had 
always spent a lot of time alone together, our parents 
were always a little too involved with their own lives to 
pay much attention to us, and we had always been fairly 
self sufficient. 

Katie was, in essence, my live in babysitter. She sort of 
surrogate mothered me all of my life and also stood as my 
closest friend through thick and thin. Although neither 
of our parents ever really sexually abused us, we were 
always very aware of what sex was and the fact that our 
family wasn't very shy about their own sexuality.

My father would occasionally walk around nude on the way 
to the shower, a huge erection leading his way. Our 
mother was known to moan rather loudly on occasion. 
Regardless, it never seemed dirty or anything, and I 
believe our parents never thought of us in an overtly 
sexual manner.

Like all other siblings, my sister and I were accustomed 
to the occasional tickle fight. These "fights" always 
started out innocent enough, but usually ended in my 
sister being angry (she really hated to be tickled). 

So one evening my sister and I were alone and I was 
feeling ornery, so I started tickling my sister as she 
lay on the couch watching TV. Katie started squirming and 
giggling, which always threw me off when she would get so 
mad. She was in her usual pink shear nightgown. It was 
worn so you could almost see her developing tits through 
the flimsy material.

As I tickled her I felt myself becoming aroused. I was in 
just a t shirt and underwear, as it was a very hot summer 
night. I jumped on top of Katie to get a better tickling 
position, and pinned her arms down with my knees. As I 
continued to torment her she began to get angry. I let up 
a bit and asked her, "If it bothers you, why are you 
laughing!"

She looked up at me and said, "You're smashing my fucking 
tit!"

I looked down and moved my knee off of her tit. The nylon 
of her nightgown was stretched taught against her 
breasts. Her tits were a foot away from me displaying 
themselves openly. They looked so plump and big with the 
way they were bursting through her nightgown. The nipples 
were erect and therefore all the more appealing.