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17.
(adjective - slang) - a person, thing or event that is disappointing, frustrating, unappealing, a bummer, a real downer; something that is not classic. Such as: "That movie was diet."
(Note: this definition, though inadvertently, was taken from Coca-Cola's choice of branding for its regular soda, Coca-Cola Classic, and it's Diet Coke. See example.)

synonyms: nasty, terrible, awful, lame.

antonym: classic, as such: "classic is good, diet is bad"; fly; sweet
Daytona Beach, FL; summer, 1987:
During the unloading of a delivery truck, most of a stack of Coca-Cola soda cans crashed to the floor in the back of a grocery store after being hit by an arriving, full palette of other goods. One store worker, trying to save surviving cases of cans from the carnage, took a lot of soda spray to his clothes, eyeglasses and skin.
A coworker, just arriving on the scene and comprehending the accident, joked, "Wow, that was classic."
"Nope," replied the worker, looking at his wet, sticky work clothes. "It was diet. It was definitely not classic."
Realizing the double entendre, a slang term was born (at least in those parts).
by ringhorne July 27, 2005
 
1.
a four-letter word that often leads to deprivation, frustration and, ultimately, failure
Diet should not be in your vocabulary.
by Claudia January 16, 2005
 
2.
A word used by large food corporations to decieve old/fat women and men into believing their product is actually remotely healthy.
Diet coke, Diet Pepsi, etc.
by Austin Kennedy July 19, 2006
 
3.
A PERMANANT EATING LIFESTYLE. Almost ALL Americans misconstrued (misinterpret) this word as a temporary change in eating habits to loose weight - such as a "protein diet"
Many Americans have a very unhealthy diet of fast food and pizza.
by Bomni February 08, 2005
 
4.
A form of torture, hence "Die" with a "t" at the end
Oh man, I shouldn't be eating so much ice cream, I'm gonna have to go on a diet.
by superblackeagle January 27, 2008
 
5.
n. A food consumption pattern lazy people take up in the place of regular exercise in order to lose weight.
Atkins, Jenny Craig, High Carbs, Low Carbs, All Protein, No Protein, No Red Meat, No Starch, No Sugar, etc.

Steve: Hey want to go eat some food?
Janet: No thanks, I'm on a diet.
by JimChach March 15, 2004
 
6.
Dare
I
eat
this?
I use the DIET method to lose wait by asking myself "dare I eat this?" before I eat anything.
by PersonWhoIsRandom January 23, 2011
 
7.
the thing your on today, then off of tomorrow
Today:
I am sooo like fat!!! Ima go ona diet for realz for realz. No more coco for me, ya heard!
Tomorrow:
uMMMM...them chips look good as hellz.... fuck it, im already fat, why dont I live a little?? (chomps on chips)
by MCRfan4life January 10, 2006