Watch: Horford doesn't know he's been dunked on, begins dribbling up court

Al Horford is likely to receive a good ribbing from his Celtics teammates for this one.

The big man made matters worse Sunday after getting dunked on by Kristaps Porzingis, grabbing the pretend rebound and dribbling up court.

Horford got the last laugh, though, returning the favor later in the quarter.