I have a funny story that happened many years ago, in Spain, when I was young and impressionable 
We were having a little party at a friend’s house. One of the persons in attendance was a young British lady, very cute, who was in Spain doing some sort of exchange program or something.
We were having a very nice time, but at a certain moment the British girl glanced at her watch and announced that she was sorry, but she had to run.
At least, that is what I am reasonably sure she wanted to say. Because what she actually said, in Spanish, was hilarious 
OK, here comes the (long) explanation – The verb “to run”, in Spanish, is “correr”. Intransitive verb, and everything. Now… In Spanish, as in English, when you have a transitive verb and you want to use it to express and action that you perform on yourself, you put the verb in the reflexive form: I have to comb myself, “he de peinarme”; physician, heal thyself, “médico, cúrate a tí mismo”. And so on and so forth.
Well, it seems that this lovely young woman thought that, in Spanish, whenever an action applies to yourself, you have to put the verb in the reflexive form, no matter what verb it is. So, “Sorry, but I have to run” became, in Spanish, “Lo siento, pero tengo que correrme”.
All fine and dandy, if a bit ungrammatical… Were it not for the fact that “correr”, in reflexive, although ungrammatical, has a very definite meaning in slang.
It means “to have an orgasm”.
So, what she loudly announced to all those present was, literally, “I’m sorry, but I have to have an orgasm”.
Oh, what a disappointment it was when the mix-up was solved… XD