When someone absentmindedly sings a crappy song over and over to themselves. If they don't know the whole song, they repeat the parts they do know, much to the annoyance of people around them.
Clerk: (quietly singing) "Ooh baby baby, how was I supposed to know/ something wasn't riiiiight..."
Receptionist: "Can you PLEASE stop that idiot singing! You have been singing Britney Spears for like 5 hours."
Clerk: "My God, you're right! I don't even like that song. Sorry."
To feel, dysfunctional and fatigued, from being submerged in a large crowd of idiots. Usually the case is you are sober and they are intoxicated. Usually applies to those in the Hospitality industry having to deal with drunk idiotic patrons in very large numbers. Common symptoms include but are not limited to, severe tiredness, irritability, headache, body ache, short patience, nausea and 10% tips.
Jacob - Hey did you go out for 6-Man in Manhattan Beach yesterday, it was INSANE!
Kelly - I wish, I had to work. Don't you remember? I was talking to you last night.
Jacob - Really? I don't even remember I was SOOO drunk. I feel like shit today, definitely hungover.
Kelly - Ya, I feel like shit too, I have an "Idiot Hangover"...