Slang for being left out, condescended to, or otherwise being screwed out of what's rightfully yours. The "High Hat" can be either given or recieved.
Note: Checkk out the film "Millers Crossing" for colorful usage of the term.
MARK: Hey Nick, I'm going over my Uncles tonight for a birthday party so I can't hang tonight. I'll call you tomorrow.
NICK: That's awfully strange-I heard from Adrian that yer' going to see the White Stripes. You givin' me the "high hat" fucker?!