Noun: this is the sad condition during which you think of a slang term, the meaning of which escapes you, but you are riding in the car, lost in space, or engaged in a sexual act, and therefore can't access a computer... by the time you are at said computer, the term has fled from your feeble memory.
as in " I wonder what the hell "roflcopter" means... when I get to work, I'll UD it..." 5 minutes later... "Dammit, I have Urban Dictionary Block... WHAT THE HELL WAS I GOING TO LOOK UP?!?!?!?!?"
by yamahagfy May 20, 2011