The feeling you get after a one night stand with someone you really like. Could also be called a crash after the high sex causes.
I hooked up with Cyrus last night, but I haven't seen him since. I like him so much! But now I have a hookup hangover.
the disgusting feeling you have the morning after a random hookup
- ugh i'm so disgusted after making out with that guy.
-- oh u'll get over it, its just a hookup hangover