Caouette is a very uncommon French surname, and in this song, it's used as a character's name. The song is a playful, repetitive list of people who are upset with the narrator, and each verse asks "Qu'a [Name]?" meaning "What's wrong with [Name]?"
Its uniqueness and the way it's used as a recurring, almost nonsensical element in the song make it memorable and intriguing. It immediately sets a quirky tone, inviting learners to discover the whimsical world of Serge Gainsbourg's lyrics.