A day on which you are allowed to break your diet, as complete abstinence is impossible for most people. It also provides a reward for the sticking to your nutrition plan over the rest of the week. The "cheat" can be small (e.g. a chocolate muffin with lunch), large (e.g. a fast food meal), or systemic (e.g. Full Fat Friday).
Carol: Oh my god, Jenny! I can't believe you're eating cheese!
Jenny: It's ok, Carol. Today is my cheat day.
by Matti Matti Matti January 6, 2014
The one day of the week when people dieting can eat whatever they please
Sara : Oh Jake you cock is so strong! Uh! Uh! Uh! Uh! Uh!
Jake : Yeah and your pussy is so soft! Ahhh! Ahhh! Ahhh!
Kiersten : Hey Jake I brought us some goodies since it's Cheat Day! OH MY GOD WHAT THE FUCK ARE YOU DOING!
Jake : You said Sunday was Cheat Day so I thought we could fuck other people!
Kiersten : You DUMBASS we can cheat on our diet not each other GOD DAMNT!
Sara : Oh Jake I'm CUMMING I'm CUMMING!
Jake : Ohhh! It feels so good in there!
Kiersten : JAKE GET YOUR DICK OUT OF HER NOW!
Jake : But it's Cheat Day!
Kiersten : That's It today is BEAT DAY cause I'm gonna beat the shit out of you two!
by SlopNChop March 11, 2018
A set day for completely and utterly fucking up on purpose all past progress made on your sad effort of dieting.
Girl 1: HOW THE FUCK ARE YOU EATING ALL THAT SHIT I THOUGHT YOU WERE ON A DIET?!?!
Girl 2: shhhhh...you see nothing...it's my cheat day.
by Bananamanagram January 17, 2015
The day where your allowed to cheat on anything
“Why are you cheating on the test?”

“It’s nov 9 national cheat day !”
by Akeihrabb November 9, 2019
U may cheat with a handsome guy named Dawson on November 5th
Yes you may drive Dawson’s boat since it’s National cheat day
by BBC Lasagna November 5, 2021
Doesn't exist
Guy1: It's No Nut November Cheat Day!

Guy2: And where the fuck did you find this fake news?
by Random homo sapien November 3, 2019
On November 13, it a day where us men can take a break from our fast and release our children.
Man: Hey babe let’s have intercourse, it’s the 13th
Woman: But it’s NNN
Man: Its fine it’s No Nut November Cheat Day
by whostillsaysdoodoo November 2, 2019