The feeling while drinking that you've been doing the same thing before.
"Hey, I just got a deja booze, since it felt like I've been here before drinking red bull and raspberry vodka, poured by Corey (like last morning at 5:00 a.m.)"
The instance of feeling that you have been somewhere before or met a certain person, only to realize that you were black-out drunk at the time.
Eddie: "I think I've been here before...this looks familiar."
Steve: "Dude, when would you have been in a strip mall in Tijuana?"
Eddie: "I think on my birthday."
Steve: "Ohh, you must have deja booze."
Deja Booze: like deja vu, but involving alcohol.
You can vaguely remember being somewhere, or hanging out with someone because you were intoxicated at the time.
I know I've been here before. Ohhhh yeah, I was drunk here last weekend, it must be deja booze!