I had just finished swimming one day & got into the changing room to wash up.
after showering, I got dressed & was about to leave...then I heard the door opened and in came a boy and a girl. she was probably his sister.
they had also finished swimming & came in to wash up as well. didn't know why his sister was with him, but I guess their mom had wanted the elder brother to look after his sister.
anyway, they washed up & came out of the shower. at that time, they were naked & I got an erection right away! I pretended to take off my clothes to get changed to go to swim.
when he underwear fell off, the girl stared at my erection and hairy privates. probably the first time for her, as she kept staring and staring.
the more she stares, the more erect I became. the brother also started to look at me, although no as curious as his sister. probably he has seen before.
both of them were hairless at that age. then I start to rub myself (as there was nobody else in the changing room). at that time, they had started to clean up & get changed to leave the place, when I suddenly shoot my sperm (about 5 or 6 squirts).