John Valby (born November 22, 1944) is a musician and comedian who plays in barrooms and college campuses up and down the East Coast. Using an old-fashioned piano, he creates comedic, obscene parodies of classic songs. Known as "Dr. Dirty", he typically performs in a classic white tailcoat and black derby hat. His songs and shows focus mainly on sex and racial slurs, with a mix of current and historic people and events.