Bossun combining Switch's failed inventions to save a kid's life.
After Asahina got hurt and threatened by a thug, Tsubaki takes it upon himself to avenge her, while at the same time vowing that he'll only need one punch to deal with the culprit. He takes a fairly harsh beating by a bunch of underlings before the Sket Squadarrives to clear the way. Once those are laid down, he proves that this statement of his was not hyperbole. As a result, this also makes Asahina get much more friendly towards Tsubaki.
Bossun sucker punching Kutsuwa-sensei for threatening to turn the life of Himeko (and, to a lesser extent as far as Bossun is concerned, Kiri) into hell.
After being beaten to a pulp, with Himeko captured and Switch knocked unconscious, Bossun not only manages to get back up, he goes on to single-handedly defeat four would-be Yakuza with nothing more than his wits, a bunch of pachinko balls and his hunting slingshot.