One of my early wet games, at 12 or so, when I was sometimes alone at home after school, was to literally hold on until I couldn't. If there was time, I would drink a whole lot first. This amount of holding was probably really dumb and dangerous, but I didn't know that. The loss of control when it happened was really powerful, it would come in two or three waves, and I could hold myself and fight and it made no difference. It was just like being a little kid and being desperate and having an accident, which was probably the memory I was trying to fix by reliving.
True confession: I genuinely wet my pants, completely, like this, very unintentionally, in school, in grade 12, while writing a test you weren't allowed to leave the room during. By some miracle the only person who saw never told.