Pet Peeve in French and in English

It is definitely a neat situation to be able to speak two languages with the same person...BUT recently I noticed something I really hate.

A native anglophone person trying to use a French word of which they really don't know the meaning...or a native francophone trying to use English words or describe something in English when they should just do it in French.

Obviously these two things happen when speaking with a listener who only understands that certain language (French to monolingual French person, etc) but it is only annoying when it is more efficient to use one's native language.

The origin of this pet peeve probably started à la Poste (in a post office) when my French wasn't super and I had a stronger accent. Yet, the person's English was even worse...so I just continued in French so we could actually get somewhere! It worked out easily and the woman was super.

Now, however, I use French all the time and I know that people know I can use both interchangeably so sometimes we do that. It just bugs me when someone tries to use a word they don't know. It is like a person using a "big" or uncommon word in the wrong context.... It not only doesn't make any sense but it also makes them look bad! For me the pet peeve side of it comes when it creates confusion.

I normally just do the "uh-huh" if I know what they meant to say or repeat saying the right word/phrase waiting for an accord.

One day I might throw a dictionary at them though. TEEHEEHEE.

P.S. This doesn't include slipping up and using a word that rhymes, etc. Those are just brain farts and everyone does that. I mean when someone intentionally, clearly, directly misuses a word/phrase, especially if they are informing you of something important. (So, not just shooting the ship with your pals and talking about your week. I replaced the "t" with a "p")