"Uncle Buck" is a classic but I think "Who's Harry Crumb" is very underrated. The bit where he buys the used car is one of the funniest things I've ever seen in my life.John Candy fucking rules.
After arguing emphatically with the car salesman (no audio).... Harry Crumb gets the car that he wants; and he then proceeds to drive it off the lot, right into traffic and gets T Boned. Accident = 100% his fault
Who's Harry CrumbUncle BuckThe Great Outdoors