The slang phrase from the 1920's, "All wet", describes an erroneous idea or individual.
He is all wet, for he is an erroneous individual.
To be or get really, really drunk.
Q #1. Hey man you gonna do some drinking tonight?
A. Totally!! I'm gonna be ALL WET n' shit!
Q#2. Hey man did you see Joe Joe?
A. Oh yeah. He was ALL WET!!!!
being wrong, disagreement
Baller 1: we're gonna beat you in basketbal today.
Baller 2: you're ALL WET, were gonna take you down.
1: how does this look on me?
2: That's ALL WET, that hat doesn't match that shirt.
stealing from your grandma purse is ALL WET