What is Sheldon Cooper's famous catchphrase?

Sheldon Cooper's famous catchphrase is “Bazinga!” in The Big Bang Theory. He typically says it after a prank, trick, or joke to signal that his preceding statement was not meant literally.

The expression became closely associated with Sheldon because his humor is often so dry or poorly timed that his friends cannot immediately tell when he is joking. “Bazinga!” functions almost like a verbal punchline, though Sheldon uses it with a confidence that does not always match the quality of the joke.

The word first appeared in the second-season finale, “The Monopolar Expedition,” which aired in 2009. It became more prominent during the show's middle seasons and eventually turned into one of the program's best-known pieces of pop-culture vocabulary. The show's prequel, Young Sheldon, later created an in-universe origin for the word involving a novelty company and prank products.

“Soft Kitty” is another famous phrase from the franchise, but it is a song Sheldon sings when he is sick rather than his catchphrase. “Bazinga!” is also sometimes written without the exclamation mark, but the stored answer identifies the canonical expression correctly.