way not to joke with someone

So bearing in mind the flip-flopping with customer x/y, when I'm working on customer X and I ask a question about the intentions of different networks in the activation, I get told "yes it should be 6 subnets" me: "so this one over here, since its not internet connected, that could even be one?" bearing in mind there's one device per subnet at this point. "yes, it could be one if you wanted to cut corners and not do the job properly".

I know that was intended as a joke and I'd already stormed off when he was saying it was a joke, but seriously, I feel a whole lot like I'm just being screwed around at the moment and its so not the day for a joke like that.  Especially when, since day one, I've done my damned best to make sure everything I've done for a customer isn't a half arsed effort.  Willing to bet there's already emails floating around and I'll be reprimanded.

Fuck it.  I have to work xmas and my birthday - I don't have to take jokes from anyone