Mazel tov is a traditional Hebrew expression of congratulations, long used at Jewish weddings, bar and bat mitzvahs, births and other happy milestones. Online, the phrase has been clipped, remixed and shared as a short celebration meme, often appearing in reaction videos, wedding edits and good-news posts where a spoken congratulations feels warmer than text alone. Its staying power comes from that familiarity: even viewers who do not speak Hebrew recognise it instantly as a cheer for someone else's success.