too high to function (THF); orginially called thiff, but happily shortened to tiffin'
when you get so twisted that it is impossible to function as a regular human being. Normal activities are impossible to perform due to the fact that you're high like goddamn planes.
1) "Hey man, how was your night?"
"Dude, soo good. I was tiffin' out!"
2) "Can you pick up the food?"
"Nah, I'm tiffin' too hard right now. Sorry!"