Explosion.

[A wide grin spreads across Bakugo's face when she asks that-- but he can't actually demonstrate it for her luckily.]

I sweat somethin' like nitroglycerin and I can ignite it in my palms like dynamite! One snap of my fingers could blow a hole bigger than you into the side of a building!

[Ok he's exaggerating a little bit.. it's more than just a snap but the force of his explosion is no joke.]