At job interview.

Interviewer: Have you ever thought about why manhole covers are round?

Me: It's to accommodate different body shapes of sewer workers.

Interviewer: Hahah. It's actually so the covers wouldn't fall in.

Me: It used to be like that, but they changed it.

Interviewer: What? Who changed it?

Me: The lizard people!

Interviewer: What?!

Me: * cowers in corner and hisses *