The Great Outdoors (1988)

When an unannounced, uninvited and unwelcome family of fun-loving misfits converge upon a lakeside resort to join their relatives for a summer of relaxation, the result is anything but restful in this raucous comedy starring Dan Aykroyd and John Candy. It's a vacationer's worst nightmare, as wheeler-dealer Aykroyd, his sexually repressed wife and eerie twin daughters "join" the easygoing Candy and his straight-laced clan for a season of "fun" in the sun. Unfortunately, the only thing these two in-laws have in common is their intense dislike for each other. Soon, it's brother-in-law against brother-in-law in an uproarious and hilarious fight to the finish to see which one really knows how to enjoy The Great Outdoors.