masturbating with your pants on and all done up, by placing your hand in your pocket and rubbing your penis through the pocket lining
I played pocket hockey during class to keep from falling asleep.
Scratching your nuts through your pockets, so as to discreetly relieve your itch during an event in which it would not be proper to do so.
My wife's mother just died and the rented tux was too tight. It had my playing pocket hockey all through the funeral.