This prank, which falls into that category, where a construction worker lies in wait wearing a bear costume to scare the living shit out of his co-worker is priceless for so many reasons.
First off, and most importantly, he legitimately scares the hell out of his co-worker who turns tail and runs, tripping and falling in the process. Second, the guy in the bear costume tries to chase him only to also fall down. Then, as if that wasn’t enough, another co-worker sees the “bear” and he too heads for the hills.
The pièce de résistance of it all might be when the guy in the bear costume actually tries to run on all fours and his co-workers still don’t realize what’s truly happening.
All in all I have to give this prank a solid A+.