When you go to McDonald's and ask for a McGangbang and it pisses off the cashier so he shits on your burgers and makes you put them together yourself.
Customer: "Can I have 1 McGangbang please?"
Cashier: "WTF thats not on the menu!"
Customer: "Fine I'll make it myself!"
Cashier: *Makes burgers and shits in them aka Mc Shithead*
Cashier: "Here you go asshole!"
Customer: *Takes a bite of shit*
Customer: "FUUUUUUUUUUUUUUUUUUUU-"
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.