A heavy-metal hand gesture, in which the subject holds out their hand(s), palm up, fingers broadly curled inward, as if clutching an invisible grapefruit, or an orb of majestic evil power (still invisible).
When the throwing of horns got co-opted by the widespread public to the point where they were often seen from Jonas Brothers fans, Lord Blaspherion G. McSatan decided to adopt a more metal-centric hand gesture: the invisible grapefruit clutch.
Somehow Billy's sideburns just kept getting longer, even though he always shaved right up to them. It wasn't intentional, but before he knew it he looked like a 1971 Cincinnati bartender. Sideburn creep had claimed another victim.