You could also just look at the punch itself. First of all, the kid just watched as the other guy jumped a table and came flying at him. As for the punch, it's clearly fake because if there were any impact, his arm and fist would have stopped upon it, at least for a moment. Instead his fist just glides across his face like butter. Regardless, it's a pretty good fake and a pretty good .gif in general, so OP has my upvote.