Freudian Slip Day(s)/Week/whatever — Truth day is when you can only speak the truth. Freudian Slip Day is when you can only blurt out exactly what you're thinking.
Also, casting votes for Road Not Travelled, Blast from the Past, and Reno mun's suggestions (YAY CRACK AND POETRY) :3 Runners up: Seven Deadly Sins and the almighty DINOSAUR INVASION DAY