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!
A scary movie, typically a horror movie. Although the term may be used to refer to scary movies more generally, a "scratchie" refers to a scary movie with a evil character that scratches.
A term used to accompany the theft of someone's stuff. Not burglary style, but while they are there and not paying attention. Usually for stealing food.
A: Dude, can I have a french fry?
B: No, fuck off.
5 mins later
A: *Takes fry and eats* "Snatchies!"
or
"Dude, I'm glad that cop was asleep when we blew past him at 90!"
"Yeah especially 'cuz you're not allowed to drive after nine and we're drunk!"
"SNATCHIES!"