Coker's first appearance in Mad was in 1961; he has since gone on to illustrate over 375 articles for the magazine. Beginning in 1967, Coker was a production designer on more than a dozen Rankin-Bass specials and shorts, including Santa Claus is Comin' to Town, The Year Without a Santa Claus, Rudolph's Shiny New Year and The Easter Bunny Is Comin' To Town. In 1968, he illustrated the Mad paperback "MAD for Better or Verse"; written by Frank Jacobs, it was the first of eight all-new paperbacks drawn by Coker. In 2002, the magazine also published a collection of "Horrifying Cliches," the long-running feature that featured Coker art. Coker collaborated with writer Don Edwing on two comic strips: "Lancelot" and "Horace and Buggy."