Francophonie· easy
casser les pieds
“to break the feet”
Meaning
to annoy someone
Explanation
This popular expression means to get on someone's nerves or to bother them.
Example
Tu me casses les pieds avec tes questions!
You're getting on my nerves with your questions!
Origin
19th century. 'Casser' here meant 'écraser' (stepping on), which is predictably annoying. French has a whole pattern of 'breaking' body parts to express irritation, like 'casser les oreilles' (to break the ears).
Source