bite one's head off
To overreact to a trivial mistake another person does.
<Person A> Excuse me, where is the bathroom?
<Person B> What are you, lazy? Why don't you just look for it yourself, instead of asking some random person where it is? People like you are the reason America is known as the laziest country in the world!
<PA> Geez, what's your problem, you didn't have to bite my head off!
<Person B> What are you, lazy? Why don't you just look for it yourself, instead of asking some random person where it is? People like you are the reason America is known as the laziest country in the world!
<PA> Geez, what's your problem, you didn't have to bite my head off!