I'll be in my usual pub which will undoubtedly be full of rag students. You wont know they even support United unless they're winning though as they'll be plain clothed and quiet. I'll be the one in there that's kicking every ball with the team like a nervous lunatic.
I've noticed that whenever I go to pubs to watch derby games, I know instantly who the City fans are, because they look visibly nervous. I went in one pub in Cheshire to watch the derby a few years back and picked out about five City fans. I thought we were the only ones watching the match, until United scored in the last minute and the whole pub erupted behind us. They hadn't seemed the least bit arsed about it five minutes before-hand.