Jun-Min is part of an all boy street dancing group. This means he basically goes around the streets of Korea with his group dancing ti whatever K-pop song they play. Groups like these are very selective as they only choose people that can dance as sharp and good as the real idols.

One day his group was dancing in the street the same time your all girl group was dancing. The leaders of the group arranged a collab which is common in these type of things which means both groups dance together.