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6.
The unusually large people that sometimes work in fast food.
Dang, that Mcfatty needs to lay off the fries.
by bajabeetle March 23, 2007
 
1.
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
 
2.
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.
 
3.
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 17, 2009
 
4.
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 06, 2009
 
5.
1.)Anyone in the Prince of Tennis fandom.

2.)Fangirls

3.)Yaoi Fangirls

4.)BNF's

5.)Anyone who ships fictional characters together.
Bobbissimo is a Mc Fatty, who has jiggy arms.

Prince of Tennis fangirls are all Mc Fatty's.

by bookshop July 13, 2007
 
7.
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 15, 2005