When a really disgustingly annoying buff guy from across the given area is undressing you with his eyes. Please note that this "moncher" will never actually come up and talk to you, he will just stare and creep you out... also, he will tell his buddies how hard he wants to do you.
"Oh my god, seriously? That dude is a total monch! Lets get out of here before he can point us out!"
"Yeah totally. I'm tired of being monched on."