A representation of "the horns", a metal salute which was first performed by Ronnie James Dio.
It is used by metal fans as general symbol of the affirmative, which could be anything from "hey man" to "fucking awesome" to "later"
it has recently begun to be used by people who are fans of other music genres and simply believe it is trendy to do. These people ar posers and are beneath notice.
"I just scored tickets to Wacken!"
"m/"
"later man