5. 'The Gang Solves the Gas Crisis' (Season 4, Episode 2)
Some IASIP episodes unpack the very essence of the series, while others just set the wheels of the shenanigans in motion and watch them spin madly out of control. This one does both. Charlie, Mac, and Dennis try to become independent oil brokers by siphoning gas and selling it door-to-door. But the main reason this is one of the best-remembered Sunnys is because it defines the gang's archetypes whenever they embark on another A-Team/Ghostbusters/Ocean's 11-style mission. Mac is the brains (which is terrifying in and of itself); Frank is the muscle; Dennis is the good-looking one; Dee is "the useless chick." And Charlie? He's the wild card, bitches!