I want to piss in peace !

When i go to the john to take a leak, i always get a hard on, that means i have to wait for minutes to get my dick into a flaccid position so i can pee co-workers make fun of me for that, they say i spend half a hour waiting, then 2 minutes peeing is there a way i can kill my dick, so it will never be erect anymore? I want to piss in peace