I don't think "blank check" means what you think it means.

Explain why you think this is funny.

What is this I don't even

By 'dues' he meant 'minimum payment'.

Also, I don't believe that this is a functioning joke. It is certainly some words, I'll give you that. It seems to misunderstand what a blank check is and what it can do.

CSB: My grandpa actually used to send blank, signed checks to pay his bills, and the company would fill out the "pay to" and amount fields for him. I doubt anyone does this any more though!