Francophonie· easy· informal
avoir la banane
“to have the banana”
Meaning
to be in a cheerful, happy mood
Explanation
Said of someone with a big grin on their face, on top of the world for no particular reason.
Example
Depuis qu'il a reçu la bonne nouvelle, il a la banane.
Since he got the good news, he's been beaming.
Origin
The curve of a banana looks a bit like a big grin, and the phrase caught on this way during the 20th century, first written down in the 1960s.
Source