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?
Similar thing happened to me with the Spanish speaking coworkers Lol. I wanted to ask a new guy his name (but trying not to say “¿como te llamas?” Which means "how are you called?) and accidentally asked for his number.
Nombre ≠ numero
I had an ESL coworker make a similar mistake to me. Mixing up name-nombre/number-numero goes both ways.