It literally means somebody whose face is like a girl's vagina. It's like calling someone a fuck-face or dick-head.
This word consists of two Nepali words words: 'puti' (Vagina) and 'mukhe' (having a face like..).
It's not a common word in streets of Nepal as I made it myself. :) Call your friends 'putmukhe', they won't know what you are talking about. Or may be they will like their new name!
Jimmy shouts: "Move on, sand nigger!!"
Kumar stops and thinks for a while....
Kumar: "Shut up, you putmukhe.