Why do I need to know Comme chien et chat?

Because the expression might date back from the 17th century, the French still love to use it when two people constantly disagree. 

What does it mean? 

Comme chien et chat is quite similar to the English ‘Fighting like cat and dog’, except that in English you fight like the two animals, whereas in French you can simply be like a dog and cat. Also, the two countries have the animals in different order. 

Both phrases are used to describe two people in constant conflict.

In French it can be used as Être comme chien et chat – To be like dog and cat, or S’entendre comme chien et chat – to get along like a dog and a cat (ie not well). 

The idea that dogs and cats hate each other dates back to the 16th century. At the time, the expression used – Être amis comme chien et chat – to be friends like dog and cat – was a bit more ironic. 

Use it like this

J’aimerais les inviter à dîner, mais ils s’entendent comme chien et chat ! – I’d like to invite them for diner, but they fight like cat and dog!

A chaque fois qu’ils sont ensemble, ils se comportent comme chien et chat – Every time they get together, they end up arguing

Synonyms

Se disputer – To fight

Ne pas s’entendre avec quelqu’un – Not getting along with someone. 

Avoir une relation conflictuelle – To be in a conflicting relationship.