You know what is a K-pop Random Dance? It's a known concept, chorus of kpop songs plays and you have to dance if you know the choreography, peoples are waitng on the left or the right (or both sides) and if you know the choreography, then you have to go to the center...

A day, a K-pop cover group on Strasbourg set an K-pop random dance in the city, you were a part of this group

Jungkook was here too because he wanted to spent vacation far from the fame, so to stay hide from the fans, he had a mask, a hat, and sunglasses, and this random dance caught his attention, so he went to this