AKA New Years Day (not to be confused with New Year's Eve)
It is called Hangover Day because..
well it's obvious
everyone has a hangover today because of excessive drinking at New Year's Eve parties.
Sober Person: Hey Lofonduh, wanna go to the mall today?
Lofonduh: Naww.. my head hurts too much.
Sober Person: But no one will come!
Lofonduh: That's because it's Hangover Day.
16👍 5👎