Paraphrased with imaginary ending:

Me: Ok so this X will never be more than Y items and not more than one pages?

Person: Yes. it won't be more than Y items and never more than one page.

Me: If this is always Y items or less and not more than one page, I can hammer this out quick then. If it is more than that it will take much longer to complete.

Person: Awesome!!!

-later-

Person: OK here's the template for Y x10 items and multiple pages.

Me: Oh I'm sorry, we're going to have to stop working on this. I thought you actually gave a fuck about this 'important' project and that you had deadlines you cared about, but apparently not enough to participate in this conversation with any level of intellectual honesty. Please fuck off now while I go work on more productive tasks....