Derived, or rather butchered from the French word "connaisseur".
American: Wow he knows a lot about wines, what a connoisseur.
French: Do you mean connaisseur?
American: Oh look, a dayjavoooooooooo
French: Do you mean deja vu?
American: OMG pff shut up, the French don't know anything we saved your ass in WW2.