I studied French for four years and I'm sure there are all kinds of things that I say in that language that would confuse native French speakers as much as François Valentin confused us with an errant use of "pet peeve".
My favorite is when a French colleague wanted to send some "demands" to a customer. He meant "questions", "demander" = "to ask", he didn't realize that "demand" has a very different implication in English. Fortunately this was caught before he sent that email.
I think he probably meant to say, "pet projects".