Sázka pro dva (1978)

Ales, a student, is sitting in a cafe and a beautiful girl catches his eye. He proposes marriage and the girl agrees. It is a student prank. Ales and a bunch of his friends have made a bet to have a mass wedding. And the next day they'll divorce, because it's supposedly possible according to the law. But it turns out the law is no longer in force, which the newlyweds find out when they leave the town hall.