The act of scratching a friends head, usually when they are depressed, drunk, or high. There is a rumored second G Spot on one's head which can be stimulated through the act of head scratchies, and therefore should be something not done in public.
Nikki: I've been feeling pretty down since I found out I was pregnant, can you give me headscratchies?
Erin: Sure thing, you better pay me back though!
1. Noun. Any particularily puzzling event or object which prompts a puzzled scratch of the head.
2. Head scratch. Verb. Most common reaction when one spots a set of man boobs - especially when the man who is sporting the boobs is not exactly large or fat, and the occurance of the man boobs is puzzlesome, prompting the observer to scratch their head in curiosity
(Jeny scratches her head, looking puzzled)
"Jeny, why are you scratching your head?" asks Michelle.
"Well, look." (points toward a young man.) "He has man boobs... but he isnt fat." Jeny replies.
"Hmmm," ponders Michelle. "Thats a real Head Scratcher."
Why can't Jake get any action? He's a pretty nice dude and seems to do everything right but the guy can't get laid for shit. It's a real head scratcher...