An example of what I mean:

I, in China, told an English speaking Chinese friend I needed to stop off in the bathroom to "take a shit."

He looked appalled and after I asked why he had that look, he asked what I was going to do with someone's shit.

I had not laughed so hard in a while, and it totally makes sense.

I explained it was an expression for pooping, and he comes back with, "wouldn't that be giving a shit?"

I then got to explain that to give a shit means you care and I realized how fucked some of our expressions are.

What misunderstandings made you laugh?