Word of the week: I'm not buying it

This week's expression is

to buy something (not in the literal sense) 

which is used to say that you don't believe something, that is to say, you don't accept the truth or feasibility of something. 

Examples:

You can tell me the same excuse as many times as you want, but I'm not buying it.

The police officer didn't buy my lame excuse for speeding. 

                                            You could say that you were ill, but I don't think they'd buy it. 

Can you think of a Spanish translation for this expression? 

Write it in a comment!