There was a weird kid in our class, who whenever he crossed behind me to get to the next urinal, would laugh: "HA! BUM-BUM!"
It always kinda embarrassed me, but not too bad as he was a bit 'special' shall we say, so no one else laughed or joined in.
After a while my friend Sean showed me an absolute game-changer revelation, in that you don't have to pull your trousers and pants all the way down, you can just pull it out through the fly!
After I'd learned this new ingenious way to pee, that was the end of "Ha, bum-bum!"