In Bed with Santa (1999)

In what MUST be one of the WORST ideas in Christmas-party-planning history, Swedish homemaker Sara decides to celebrate the Yuletide season with her three ex-husbands and their families. Her current spouse Janne is initially quite opposed but eventually gives in. Then the booze kicks in. Families start in-fighting. Janne grows more and more annoyed as the guests keep referring to having sex with his wife. And during dinner, Sara announces she is pregnant--quite the surprise for Janne, who had a vasectomy the year before. Soon the party devolves into utter chaos.