"You Don't Know" is a song by American singer-songwriter Cyndi Lauper, released by Epic as the first single from Lauper's fifth album, Sisters of Avalon (1997). Remixes of the song were made by several producers such as Tony Moran and Junior Vasquez. It peaked at number 27 in the UK, while peaking at number 16 on the US Billboard Hot Dance Club Play chart. The song contains the word "bullshit" and was not edited out of the UK singles as is typical. While performing on several UK shows, such as Noel's House Party, she skipped the word. The music video for the song was directed by Lauper.