Helene Fischer is a 30-year-old German singer, and last Thursday she held a concert in Munich.
During her performance, one fan in the crowd managed to hand Helene a Borussia Dortmund scarf, which the singer duly held on stage.
Helene Fischer is a well-known Dortmund fan.
Many in the Munich crowd were unhappy by that, and the Bayern supporters in the audience quickly made their presence and feelings known.
The crowd initially jeered the singer, before the Bayern fans began to loudly cheer for their team.
See the footage of what happened when Helene Fischer received a Borussia Dortmund scarf during a concert in Munich below.