Originally a nickname used to refer to former U.S. President Richard Nixon
. It was actually coined by Democratic politician Helen Gahagan Douglas
during the 1950 U.S. Senate race in California because of Nixon's usage of dirty tricks to gain an advantage. It's often incorrectly assumed that the nickname was invented because of Nixon's involvement in the Watergate Scandal, when in reality the scandal was just another instance of him being the Tricky Dick that we know and love.
Sometimes the name is reused in reference to Vice President Dick Cheney
for no particular reason.
Also, a very thing to call anybody who prefers to be known as Richard, Dick, or Dickie (in which case the name can become Tricky Dickie).