A person who arrives at an event/gathering in an inappropriately advanced stage of inebriation, and attempts to socialize with the other attendees as if nothing were out of the ordinary, is "unexpectedly drunk"
Antoine arrived at the wedding rehearsal a few minutes late, acting more relaxed and jovial than usual. It wasn't until he vomited on the bride's father, and attempted to use the bride's sister as a handkerchief, that people realized he was actually unexpectedly drunk.
by FriendOrFlake July 21, 2014