What does it mean?

The dictionary of the French daily Le Parisien defines chiottes as “a room containing a container allowing a person to indulge his urination or defecation needs.”

In other words, chiottes is the French term 'loo' but it's not one to use in polite society. This is slang, so Aller aux chiottes is equivalent to 'hit the can' or 'head to the crapper'.

It comes from the verb chier, which means to 'shit', a less nice way of saying faire caca – 'take a dump'.

Like the French use both the plural version of toilette – je vais aller aux toilettes or au toilette both mean 'I'm going to the bathroom – you can use both the single and plural version of (la) chiotte.

NB! The term chiottes is very colloquial and you should refrain from saying it if you are in presence of people who might find vocabulary such as the French equivalent of 'shit' vulgar.

Use it like this

However, if you are with friends at a bar you could say

Je vais aux chiottes, j'arrive. – Just got to hit the can, be right back.

Elle est où Théo ? Il est partie au chiotte. – Where's Theo? He just popped to the loo.