avoir d'autres chats à fouetter

to have more important things to do

This expression means to have better things to do or more pressing matters to attend to.

Je ne peux pas t'aider maintenant, j'ai d'autres chats à fouetter.

I can't help you now, I have other fish to fry.

From the 17th century. Related to older sayings like 'éveillé comme un chat qu'on fouette' (alert like a whipped cat) and 'il n'y a pas de quoi fouetter un chat' (not worth whipping a cat over, i.e. it's trivial).