Not to look at gift horse in the mouth

Question

I understand the meaning of the saying and the context it’s used in.

What I don’t understand is why you would look a horse (or gift horse) in the MOUTH. What is special about its mouth?

In: Other

Answer 1

ELI5 – it’s a way of saying “when someone gives you something for free, don’t check it’s quality right in front of them.” Accept their gift and thank them for it. Don’t be rude.