1) Horny teenage couples in their droves flock to McDonald's for cheap, disgusting "food" every weekend. Sometimes, dipping the fries in those nasty little ketchup tubs gets too sexually suggestive for them, and they head off to the toilets to bang each other. They think it's risque, but almost everyone in McDonald's has no soul and no shame; their faces are deeply buried in greasy, supersized crap, so they barely notice the kids sneaking off for a McFuck.

2) McDonald's employees that are shagging at work are "McFucking". Presumably, the experience of being "Mcfucked" would lead to some serious "McShame", but as afore mentioned, those that spend large amounts of time in McDonald's have no souls, or personalities for that matter.
"Shall we go to McDonald's and get a McChicken Sandwich? We could sneak off for a quick McFuck too, if you wanna?"

"Norman and Shirley were McFucking at the end of last night's shift. I only noticed because I'm new here and still could go to heaven"
by MagickDio March 07, 2010
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Verb, used by a pissed off McDonald's employee.
Employee to Annoying Kids: Hey, you nd your friends get the mcfuck out of my restaraunt!!
by Matt-0 June 17, 2009
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An individual that truly has no soul. Often referred to as a zombie, squeaks like a little girl, complains continually, cries over frivolous activities, and frequently urinates the bed like a little girl afraid of the boogie man in her closet.

Often Referred to as the mythical character "Salad Fingers" because of this individuals insatiable liking of rusty spoons and collecting hair and fecal matter.
You're such a McFuck! Stop licking all the damn rusty spoons!
by Salad Fingery February 20, 2011
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1. someone you fuck without emotional attachment.

2. a "fuck buddy" that only temporarily fills a void.
"I was going to call my ex-girlfriend and see if she wanted to hang out for a while, but I was feeling lazy so I just called up my McFuck and fucked her in the Chic-fil-a parking lot."
by oodunkin April 25, 2010
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