My brother is a fire hazard

So I told my brother to defrost some pieces of bread in the microwave for 3 mintues, a few minutes later I go in the kitchen to find my brother had put the whole loaf of bread and the bag it came in cooking in the microwave for 20minutes. I immediatly stopped the microwave but the bag was so hot I couldn't touch it, if it had been left in there for 20 minutes it would have caught FIRE!! Oh the genius of my brother is outstanding (insert sarcasm here.)