Family Guy (1999)

S4E6 Petarded

Following his victory in Trivial Pursuit, Peter feels he's a genius. To challenge this belief, Brian encourages him to take the MacArthur Genius Grant test. The results, however, reveal that Peter is actually mentally challenged. He initially enjoys exploiting this newfound status, but things take a turn when Lois gets hurt, leading to the kids being taken away due to Peter’s inability to care for them responsibly.