As TV Tropes explained:
"When fighting, two (or more) animated or comic strip characters may vanish into a ball of smoke, from which the sounds of a really violent struggle emanate.
Hands, feet, or other random objects may protrude momentarily, then be pulled back in."

Battle of the bands is going on and a dispute ensures after the bass guitarist and electric guitarist argue about their performances.. And thus the reason for the fight. The Ledian drummer is witnessing this argument while the singer had to take a restroom break. pfft