Of course he thought it was a joke and let it slide with a "hm?" but he was seriously annoyed. I mean, just don't say things like that even as a joke!

I have a thing for you.

The thing is , I don't really want to.

It's not a thing one can well boast of.

I like to think things through before making a decision.

Springing things can be like a stick from a bush.

She likes to run things and be in control.

First things first, let's prioritize our tasks for today.

I need to make things right with my girlfriend.

He thought the whole thing a bad joke.