The phrases are French internet slang in miniature: deso shortens desole, tg shortens a vulgar shut up, and merci simply means thanks. Combined with roulette, a reference to random chance, the line feels like a quick verbal spin of the wheel. It circulates as a short reaction clip rather than a song or scene quote, shared for its speed and attitude. Creators reuse it when a random outcome, a roast or a sudden exit needs a fast punchline without any setup or long explanation needed.