Is the direct result of extreme munchies. You eat and you feel full - you KNOW that you're full, but you keep eating. Double full is the realization that you've gone too far - you are extremely full.
1. (After smoking, eating dinner, smoking again, and eating the leftovers)
"Fuck...I can't eat anymore. I'm going to get double full."
2. "Fuck..I can't move. I'm double full."
3. Friend 1: I didn't know which snacks to bring, so I just brought all of them.
Friend 2: Fuck..we're going to get double full.