i dont get it

When "bustin" rusty (the little kid) put the hotdog in the microwave he left the timer on maximum. Eventually the hot dog expanded so large because of the heat, it exploded. The officers thought it was shots, and in return returned fire. One of the bullets, or perhaps it may have been the explosion cause by the expanding hot dog, detroyed a bag of doritos, and a piece of it was logged into mike's cheek.

It was just shrapnel caused by the explosion. Coulda as been easily been glass, but doritos are funnier.