The parties were already wrapped up in several other lawsuits relating to the landlord-tenant relationship when the phone rang at the landlord's house at around 6 am on a Saturday last year.
It was the tenants, calling to complain that the water temperature in their bath was only 35C rather than the contractually agreed-on 40C.
When the two met in the courtyard later that morning, the landlord asked to be allowed into the flat so that he could check the temperature.
But the tenants refused, saying that the water was the same temperature throughout the building.
Court documents show that in the process, the husband lashed out with a volley of insults, including calling the landlord a “certified arse”.
A few weeks later, the landlord announced to the tenants that he was cancelling their contract without notice over the insult.
The tenant claimed he had been provoked, saying the landlord used the familiar “du” and physically attacked him – meaning that the cancellation was unjustified.
But the judge at the Munich civil court found that the insult was so bad as to breach the terms of the contract, meaning that the landlord couldn't be expected to continue renting the flat to the tenants.
The law distinguishes serious insults, which reveal the contempt of the person using them for the honour of their target, from simple impoliteness.
Calling someone a “certified arse” was an injury to the landlord's honour, the judge said, and had completely destroyed the relationship of trust between the two.
An important factor in the decision was the fact that both parties lived in the same building and regularly encountered each other – with the tenant failing to use any of those opportunities to apologize.
A spokeswoman for the Munich Tenants' Association told the Abendzeitung München that "a cancellation without notice should always be the last resort.
"This judgement reduces tenants' rights yet again. Landlords can get away with more and more. Tenants can't defend themselves, because they always have to worry about a cancellation without notice."