The Great Outdoors (1988) on Netflix

Chicago resident Chester "Chet" Ripley, his wife Connie, and their two sons Buck and Benny are on vacation at a lake resort in Pechoggin, Wisconsin. Then the unexpected happens -- Connie's sister Kate, Kate's know-it-all investment broker husband Roman Craig, and Kate and Roman's twin daughters Mara and Cara crash the vacation, having decided to blow off their own plans to vacation in Europe. Roman proceeds to majorly get on Chet's nerves -- so much that Chet is ready and willing to pack up and go home, even as teenager Buck tries to romance local girl Cammie. It turns out that the reason why Roman, Kate, and the twins crashed the vacation is because the Craigs are broke because of a bad investment, and Roman was planning to hit Chet up for $25,000.