It is in violation of the Guy code not to, when witnessing one of these creatures in the presence of friends of any gender, say "joefundo" and do the motion described below.
Simply look down at your crotch.
Guy B: Whoa, dude.... who is that?
Guy A: Looks at Guy B.
Guy B: Nods.
Both: Joefundo (Both proceed to do the "Joefundo" motion)