There's a reason why Jimmy Fallon's show effin' rocks. Fallon and Jon Hamm surprised sightseers at the famous "Top of the Rock" at 30 Rockefeller Plaza, where The Tonight Show is filmed.

Unsuspecting visitors were told they were getting their picture taken, but behind them, Hamm and Fallon were photobombing them in the most hilarious ways. All the participants got a copy of their photo afterwards.

Watch it in the video below: