Our next summer vacation classic is National Lampoon's Vacation, from 1983, where the dopey and clueless Clark Griswold hauls his family on a cross-country drive to visit the famed Wally World in California. This is Chevy Chase in peak form, as his earnest and naive all american guy persona gradually shifts to desperate and crazed as the disastrous vacation takes its toll on him. Everything that could go wrong, does go wrong, from dead grandmas to creepy Cousin Eddie (Randy Quaid) and because they didn't have to cater to the bland and destructive PG-13 rating in the 80's, there's no problem shifting tones from slapstick hijinks to subversive black comedy, which makes it even funnier and gives it an edge the later ones didn't have. Like with yesterday's pick Jaws, the sequels destroyed this franchise quickly (although Christmas Vacation has its moments), but the original still cracks me up. It's Chevy Chase at his best (also directed by the late, great Harold Ramis).
Original 1983 Trailer: