I used to spend a lot of time at my grandparents house when I was a kid. My mom and I had lived with them when my dad was in Korea so I was very close to them, especially my grandmother.
I discovered masturbation in my grandmother's bathroom around age 12. She would put her panties in the bathroom hamper every night. I always had to take a bath when I stayed over there. One night my curiousity got the best of me. I picked up her pink cotton panties from the top of the hamper and took a sniff of the stained moist crotch. It was instant wood!
I would anxiously await her taking a bath every night I stayed over there so I could follow with mine. After about two weeks of masturbating, to those delightful smelling panties, I guess she finally figured I was spending an awful long time in there taking a bath and decided to check up on me.
One summer night I was sitting on the toilet slowly stroking my small penis. I was just reaching the point of no return when my grandmother walked in, claiming she forgot something. I jumped up off the toilet headed to the tub but began shooting cum all over the place! It was embarrassing enough getting caught but to get caught while blowing a load was the ultimate shock!
Thank goodness she didn't notice the panties I had dropped to the side of the toilet. I thought I jumped up in time to get towards the tub but the five or six squirts from my boner gave me away! What agony to be having such pleasure and not being able to enjoy it while getting totally embarrassed at the same time.
All she said was 'I guess I should have knocked.'