This past weekend, Hoffenheim hosted Borussia Dortmund in a Bundesliga game. Both clubs have a tetchy relationship with each other but BVB 's away support hit a particularly soft spot with their hatred of Hoffenheim's billionaire investor Dietmaar Hopp. Hopp is not exactly popular with Dortmund.
However at the weekend, things took a turn for the worst as this video shows (4.00)
That strange noise at 4.03 is the sound of a high frequency emitting device which was placed below the away block in order to drown out the Dortmund fans' anti-Hopp chants. Basically, one of Hoffenheim's employees didn't like what the away fans had to say and so drowned them out.
The rest of the frankly unbelievable story from BBC Sport.
German club Hoffenheim have apologised after an employee admitted using a high-frequency sound system to drown out visiting fans' chants during their 1-0 win over Borussia Dortmund on Saturday.
The employee, who now faces disciplinary and legal action, deployed a sound system which emitted a shrill pitch.
The device irritated fans and disrupted their chants targeting Hoffenheim's major investor, billionaire Dietmar Hopp.
"An employee came forward and admitted that he had put in the equipment," the Bundesliga side said in a statement on Tuesday, a day after a Dortmund fan filed a police complaint for bodily harm following the incident, in which play was not affected.
The club said its employee had wanted to create an "antidote" to what he thought were unbearable insults against Hopp.
The statement added: "He also said he was unaware of the seriousness of his action which was mainly supposed to be humorous.
"Neither the club nor the president nor Mr Hopp were aware of the equipment's existence.
"We distance ourselves from such an action and apologise to all football fans if their experience was affected."
Photographs taken during the game showed a man with headphones sitting in a tunnel immediately under the travelling fans' stand with a home-made wooden construction that included two speakers.
Heidelberg police, who have asked for the apparatus to be delivered to them, are still investigating the incident.
Firstly, welcome Ligue 1, La Liga and fellow PL watchers of ONTD to the weird and wacky world of the German Bundesliga. Great NT but a mental football league.
Interestingly enough, German football rules that in the event of an illegal device being used in a match, the teams can appeal the score. Dortmund lost but they didn't appeal. Honestly, though what a weird story. IMO Hopp should be able to handle the insults. If Bayern Munich or Manchester United used a high pitched frequency device to drown out what away fans say about them then the noise would never end, it would become a part of the experience. Hoffenheim's owner needs to stop winding up Dortmund then maybe the fans would forget about aiming insults at him. .