Usually 30 minutes after the complete ingestion of a McDonald's meal one is faced with McCramps. These cramps are just like regular stomach pains, but differ in the fact that they are brought on by eating McDonalds.

Usually 10-15 minutes after the McCramps/McPains occur one will get the McFarts. These are generally farts with an odor similar to that of death. They reak and reak and generally cause people with you during that time to leave.

Finally, the McCramps get so bad that you run to the washroom and begin to expell feces. These feces are refered to as McShits. They are usually consist of diharea or some liquid and some solid parts. They also have an odor of death, and can cause one to pass out if they McShit too long. Generally, after a good round of McShits, the Large Intestine feels as if it has had an enema, and is generally happy until it one eats McDonald's again.

After the McShits subside you are done with the cycle, or your body may still be undergoing the the "McShit" process, and one will continue to McFart until the McCramps go away. That is the signal to enter society once again.
Matt: Omg Dude McDonald's is so good!
Sasa: I know, but it'll be bad later man, trust me...
Matt: How do you figure?
Sasa: The McShits bro, you'll see.

----- 30 Mins Later -----

Matt: Oh dude this is killing me! Ahh, what is this sensation?
Sasa: Thats the McCramps man... I told you!
by xSasax February 11, 2007
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The act of using the public restroom in a fast food restaurant without purchasing any food. When challenged by a suspicious manager, the assurance of a subsequent purchase of said fast food is known as a "McShit with Lies".
Dude, stop here, I can't hold it in anymore. I gotta go for a McShit. Meet me at the Drive-Thru in a few minutes.
by Cozzy August 2, 2003
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Entering a fast food restaurant with the sole intention of using their toilets. If you tell a passing staff member that you'll buy their food afterwards, you have taken a McShit With Lies.
"Right... hold on people, I need to go for a McShit."
by KHD August 3, 2003
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Entering a fast food restaurant with no intention of buying food, you're just going to the bog. If challenged by a pimply staff member, your declaration to them that you'll buy their food afterwards is known as aMcShit with Lies.
I'm just off for a McShit.
by Apple martini2 December 30, 2009
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The result of eating fast food and having to take a large and/or painful crap.
Joe: Man, Todd is taking a McShit again, he needs to lay off the McDonald's.

Andrew: Ew that's gross.
by JoeyKid July 18, 2008
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The act of going into a restaurant (particularly a fast food restaurant) in order to use their toilet facilities, with no intention with buying anything.
Assistant: "Sorry, toilets are for paying customers only"

You: "Well, I want a McShit with lies"
by hippyman December 18, 2007
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