A derogitory statement impliying that the target is a fake, douche, jerk off. Comes form the word "dildo" meaning fake penis; and the word "licker" meaning one who licks things. The combination has the implied meaning that said person is not only a"dick licker" but is in fact a "fake dick licker". Popularized by the animated series Metalocalypse.
Bono the lead singer for U2 is the biggest dildo licker in all of world history.