Krusty the Clown

Krusty was a fictional character.

Whilst outside the Railway Station giving away tickets for the museum, Odd Bob received an insult from one kid saying "Take a hike, Krusty!" (TV: The Day of the Clown)

After George Cooper claimed that President Bush's hair was green, Lauren Anderson joked to herself that he wasn't Krusty the Clown. (PROSE: Cyberon)

Information from invalid sources
Shortly after the Twelfth Doctor stepped out of the TARDIS, Krusty the Clown threw a custard pie at the camera, only for it to be licked off by Scooby-Doo. He was surprised when he saw Unikitty jump out of the TARDIS, accidentally landing a pie on his head. He later watched on as a child placed Scooby-Doo and the Ecto-1 onto a LEGO Gateway. (NOTVALID: Endless Awesome)

Other matters

 * Although not mentioned in the episode, Krusty is a character from The Simpsons.
 * Krusty the Clown appeared as a playable character in LEGO Dimensions.