Three Crazy Jerks II (1988)

Original title: Zärtliche Chaoten II

In 2043, Frank and Xaver have only one big problem with their jobs at a patent office, their boss Dr. Kneitz who's mission it is to make their life miserable. But then an unique opportunity presents itself when an inventor shows up to patent a time machine and they come up with a plan to travel back in time to stop the conceiving of their boss. Accidently Ronny, a night watchman, happens to be in the room with them when they use the time machine and so, in part unwillingly, the 3 of them travel to the year 1988 in Gran Canaria and they only have a couple of days to stop every interaction with potential fathers for the mother to be.