If you're looking for an informal greeting for your friends you could use salut or ça va, or some people like to use coucou.
You'll hear people say it to babies or children a lot, a sort of French version of peekaboo or coochiecoo, but it's also very common to hear adults use it as an informal 'hiya' or 'hey' type greeting.
In fact, when asked the majority of readers of The Local said that they either do use it or often hear it being used and have no problem with it, but when people don't like it, it seems that they really, really dislike it.
Living in France: Daily dilemmas. So this one has been the subject of some debate among our friends, but is 'coucou' ever a socially acceptable greeting between adults? Or should it be kept strictly for children?
— The Local France (@TheLocalFrance) July 31, 2019
Reader Benedicte Hamon exclaimed: “Je ne supporte pas! What a stupid expression!”
While otherwise mild-mannered Englishman in Paris – and The Local Europe's Editor – Ben McPartland is driven into a positive frenzy of irritation by the term.
He explained: “I just can't be that person who says coucou to another adult no matter how many French people say it to me.
“They might use it like “hi” but it sounds far too much like “peekaboo!” which is not acceptable to say to anyone over the age of one.
I'm not having this. I don't want to live in a world where grown French men and women greet each other with a “peekaboo”. https://t.co/BwoFJCUxLD
— Ben McPartland (@McPBen) July 31, 2019
“I personally prefer to greet babies under the age of one with a Bonjour, comment allez vous? rather than coucou“.
Persuasively as he makes his case, however, it seems that he is in a minority on this one.
Yuri Mashtalir said: “I use it all the time. It's basically equivalent to salut for me.”
Cathy Hearn also approves, describing the term as mignon (sweet) while Camille adds that she uses it with “friends and lovers”.
Jeanne Darm pointed out: “It may not be acceptable but it's accepted. What about bye-bye in the US, then?”
Assunta Vincent said: “Obviously it is acceptable… only among friends, or people you are closed with, even colleagues. Don't go saying this to your chief, though!”
Its origin as a greeting is a little obscure but the word also means Cuckoo in French, so it's possible that it began as baby talk from people imitating a cuckoo clock to play peekaboo and amuse their babies.
French dictionary Larousse defines it as a way to “cheerfully attracts someone's attention when you show up by surprise”.