The phrase "that's what she said" dates back decades as a schoolyard joke, but it exploded into mainstream culture through The Office, where Steve Carell's Michael Scott used it constantly across the show's run starting in 2005. It became one of the most quoted lines in sitcom history and migrated into memes, reaction videos and soundboards as the go-to punchline for accidental innuendo. Its staying power comes from how easily it slots into any conversation where a harmless sentence can be heard another way.