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1.
Derived from the word shack and flashback, a shackback is the act of reminiscing about shacks from weekends past. Shackbacks are usually shared with the two individuals who shacked together. See shack. Because shacking occurs commonly when both parties are intoxicated, conversations or actions that took place during and before the shack are easily lost in the fog of drunken memory, and thus, (attempting) to recall events from a particular shack can be quite humorous, if not slightly embarrassing.
G1: Last weekend's shack with you was spectacular!

G2: Indeed! I could say the same for you darling! I don't recall all too much from that night because I was totally smashed. But I remember dropping you into a bike rack while carrying you out to the taxi before we got back to the house!

G1: So that's why I have such an unsightly bruise on my hip! Ha ha ha! Oh, shackbacks!
by Sir Gregors November 28, 2009