Soggy Sandwich Day
Soggy Sandwich Day is on May 17th and is celebrated by spilling any beverage, on anybody's sandwich, whether it be your own or a friend's (it is required that you say "Soggy Sandwich Day!" before spilling the beverage on a friend's sandwich).
You: Hey dude, guess what?
Dude: What?
You: ... It's Soggy Sandwich Day (proceeds to spill beverage on sandwich)
Dude: AHHHHH
Dude: What?
You: ... It's Soggy Sandwich Day (proceeds to spill beverage on sandwich)
Dude: AHHHHH