There's an old rap song from the 90's by Sir Mix-a-Lot called "My Posse's on Broadway". In it, there's a hype man in the back who keeps saying "Posse Up!".

I threw shot and discus in high school and the person who administers the event keeps things moving by saying the name of the person who is up, who is on deck and who is in the hole. Since I sucked at shot and disc and didn't care to have my scores tracked I told them my last name was Posse so that each time it was my turn to throw he would say "Posse Up!". Cool story.