Carry On Behind (1975)

Professors Vrooshka and Crump decide to visit an archaeological site to study the artifacts there. Lo and behold, it's right next to a caravan site where all manner of people are staying. With a randy Major owning the site, a snobbish mother, and the two professors' constant innuendos, the film ends with a sinking caravan site and a striptease performance as a replacement for the cabaret night.