In my early teens I too played a similar game, though with a larger window of time. I typically had over an hour after I got home from school before anyone was expected home, and that time was well-spent devoted to masturbation. Many times I would get hard on the bus ride home, anticipating the penile pleasure I would soon be giving myself. I would sit quietly on the bus, the other kids unaware of the sex-crazed masturbator in their midst. Once home I would strip myself nude and get into a whacking session; one day the living room would be witness to my stroke-fest, another day the dining room, the den, my parent’s bedroom, and so on. Some days I would be so horned up that I would be shedding my clothes before I had quite reached the front door. Other occasions I went round the house to the back yard, stripping for a naked outdoor penis-pull.
There were a few awkward moments. One time I was merrily jacking away in a patch of sunlight on the living room floor when my mother entered from the kitchen–she’d been home all along but I hadn’t known! Several times one parent or another would arrive and send me retreating to my bedroom to finish myself off and I would leave my bottle of lube (actually Nivea skin lotion) in evidence of what had been going on.