Bee is CH ShoGun's The Bee's Knees

The phrase "the bee's knees," meaning "the height of excellence," became popular in the U.S. in the 1920s, along with "the cat's whiskers" (possibly from the use of these in radio crystal sets), "the cat's pajamas" (pyjamas were still new enough to be daring), and similar phrases which made less sense and didn't endure: "the eel's ankle," "the elephant's instep," "the snake's hip."