For reasons i don't understand i was afraid to pee at the middle school in the 60's. I always held it until i hit the woods on the way home. My little sister was one year behind me so in grades 8 & 9 i had to walk her home. She quickly learned my secret fear since every single day i stopped just as we reached the woods. Soon she couldn't resist spying around the tree. I still decided that her watching was still better than doing it at school. Soon she kept lookout for me and i let her watch close up every day which she really liked even when i had to poop. It was our private secret.
Ther were days i couldn't pee because of am extreme hardon so i jerked off in front of her so my dick could relax enough to pee.