What the drive-thru cashier must smoke in order to suggest super-sizing your meal 5000 times a shift,25000 times a week, millions of times a year,billions and billions served.
"Welcome to Mcdonald's. Can I take your order? **snort**"
My mother-in-law and I gave each other a knowing look. The loudspeaker snort was a dead give-away for Mcfatty inhalation. We bummed a couple of tokes in order to keep quiet, and then headed to the motel with our post-coital snack.
by pantaloon January 24, 2008
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1) A person who is moderately to morbidly obese from eating mass quantities of McDonalds food. Usually an American.

2) My middle school religion teacher, Ms. Miles
(Please don't give a thumbs down because of this definition. The one above is the real one.)
Ms. Miles.

Look at that blob waddling down the street. That lady, Ms. Miles, must be a Mcfatty.

Look at Ms. Miles, my middle school religion teacher, stuff her face with that Big Mac. She is a Mcfatty.

Since look at all those tools, including Ms. Miles, standing in line in Mcdonalds. They are all Mcfatties.

The Mcfatty devoured 3 Big Macs and a large fry in one sitting. Her name is Ms. Miles.

When the Mcfatty, Ms. Miles, walked down the hall, I yelled "Earthquake" because she was so morbidly obese the building shook as she walked.

I yelled "Look out!" as the Mcfatty, named Ms. Miles, slowing jiggled towards Will. He would have been trampled and crushed to a gruesome death if I didn't admonish him of the corpulent whale approaching.
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someone who has become so fat that they cant accomplish simple tasks

one who gets a work out from climbing stairs
that dude is such a McFatty
by jason1228 December 6, 2009
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That guy has been eating McDonald's all this week. He's starting to become a McFattie.
by RickrollingIsOverrated July 5, 2009
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slang for the evil corporation usually called McDonald's, due to the high amount of fat in the food served there.
Todd: "Hey, wanna go to McFatty's??"
Jena: "Nah... I'm on a diet"
by Teh Franilow April 18, 2009
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A male or female who is in the class of gargantuan size due to the mass consumption of McDonald's.

A male or female who consumes more McDonald's then he/she consumes oxygen.

Copyright: Joseph M Burns
Man that chick over there just downed 5 BigMacs, she's a real McFatty.

That dude comes in 3 times a day, 7 days a week. Doesn't he have a life? What a McFatty!

Joe has his girlfriend Carmen, who works at McDonald's bring him mass amounts of food after every shift, he's a McFatty.

Bailee did not copyright the word McFatty. Joe did!
by jburns1204 July 27, 2015
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An awesome MCconcoction that consists of a MCchicken piled onto a double cheeseburger with bbq sauce added.
Me: "The Mcfatty sounds like the grossest idea since the roman helmet."
n00b: "GOD I love mcfatties!"
by NicholasridiculouS November 16, 2005
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