"On Parks and Recreation we have this casting rule that we call the Poehler Doctrine. In season [two], there was a guest character that called for a handsome, hunky police officer who Leslie Knope was going to date. Amy suggested Louis C.K., and I said, 'He doesn’t match the profile.' Her response was, 'Who cares? He’s hilarious.' I agreed, and from that point forward, even on Brooklyn Nine-Nine, our M.O. is to cast the funniest people for the part."
-Parks and Rec/Brooklyn Nine-Nine co-creator Mike Schur in about why he doesn't care about stunty guest stars and just wants to hire super funny people.