@wundayatta : Well, “fuck you” is more “va t’enculer” (literally “go get fucked in the ass”).
Where it gets tricky is… “un baiser” is the noun form of “a kiss”. But “baiser” is the verbal equivalent of “fuck.” So “je veux te baiser” means “I want to fuck you,” rather than “I want to kiss you.”
According to someone wise on wordreference.com, this all goes back to the decadent courtly word games in the court of Louis XIV. “Baiser” originally means “kiss,” and these foppish courtiers thought it would be cute to use the word “kiss” as a euphemism for “fuck.” And that is how it still used.
I just try to avoid using the word entirely, haha.