The word "ketchup" in this song is a playful and clever use of French slang. While it literally refers to the condiment, in this context, "Ça va ketchup" is a phonetic play on the English phrase "It's gonna catch up."
Naza uses it to mean that things are going to intensify, get crazy, or that consequences are about to catch up with someone. It's an engaging and memorable word choice that highlights the creative use of language in French music.
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