Coucou ? What does that mean ?
Coucou is the french word for cuckoo (the bird).
It's also the perfect translation for "peek-a-boo !" or "hi !".
That's why coucou is one of the most popular word in french.
Coucou ! Comment tu vas ?
--> Hi ! How are you ?
You can say "coucou" to a friend, colleague, family member.
Do not tell it to someone you don't know or someone important (your
boss, your teacher...)