When a girl or guy (depending on their preference) has either sucked, fucked or given a handjob to 5 or more dicks the previous night, and following the next morning, they are so tired from the previous night, that they have a "dick hangover". Usually applicable to hookers.
Girl: I'm sooo tired from last night
Guy: What did you do?
Girl: Fucked 7 guys at once. Now I've got a dick hangover.