The legendary goop from which all McDonald's menu items are derived. Chilled and pooped out of machine into a cup, it's a shake. Baked in an oven, it's a bun. Grilled, it's a burger. Molded different ways and fried, it's french fries, chicken nuggets, onion rings, etc.
Generally anything that comes from a McDonald's restaurant.
Also anything that's cheap, abundant, undesirable and valueless.
Whilst receiving deep-throat fellatio from a woman, one may stuff one's ballsack into the woman's mouth at the same time, the sheer volume of which causes her lips and cheeks to stretch wide open (as though she's making a big happy smile, hence it is sometimes referred to as a happy meal.)
Man, look at the mouf on that chick... I'll bet she'd love a nice Sausage Egg McStuffin for breakfast.
Where you know you aren't full because you didn't eat to your capacity, but you ate McDonald's, so you feel absolutely horrible and sick to your stomach.
Today i had the urge for something light that could hold me over for a few hours, so i went to McDonald's and bought a burger off the dollar menu. After eating this i was so Mcstuffed i couldn't even have dinner...