what does 'bite his hand off' mean

[Infin1ty]

Mike: 'He offered me a 50% discount. What should I do?'
Jane: '.........'

(a) Hold his hand down.
(b) Bite his hand down.
(c) Hold your hand in.
(d) Bite his hand off.

The correct answer is D, but what exactly does 'bite his hand off' mean? It sounds like 'cut off sb's hand by teeth to me.
_________________
Today is a gift, that's why we call it the present.

[Alan]

Hi,

This is an idiom and means: accept the offer immediately, without hesitation. The idea of 'biting' suggests dramatically that you should accept the offer that he's making with his hand and not only grab it but bite it off!

Alan
_________________
English as a Second Language
You can read my ESL story 'the' vs. 'a/an'

[Infin1ty]

Thank you for your explanation.
_________________
Today is a gift, that's why we call it the present.