A nose rogue is a long nose hair that has extended some distance below the nostril and is highly conspicuous and unsightly. It is generally more common in men than women.
It is generally decent for a man to warn another man if he has a nose rogue, but women will not do this unless the man is her boyfriend. Normally a woman engaged in coversation with a man suffering a nose rogue will simply end the conversation quickly to escape.
Note: A nose rogue generally refers to a stray hair, but may also refer to a conspicuous booger.
Bob: I thought you were gonna score with that chick for sure, what happened?
Jimmy: I don't know dude!
Bob: Oh wait, I see it, dude you got a nose rogue.
Jimmy: Aww f*ck!!