It's the effect greasy, nasty fast food has on you about 15 minutes after you eat it: You feel lethargic, tired, not wanting to do anything but veg on the couch.
Well this sucks. I just got a McHangover from that Big Mac super sized meal.
When you eat too many chicken nuggets and feel too bloated to get up so you fall asleep at the table next to all the extrafood and wake up feeling sad that your leftover fries are now stale
"I ate too many chicken nuggets last night and now I have a McHangover, bro."
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.