Never mind all the fuss about whether or not the Joker has a boner... here's a villain whose name now means "an oral sex act."
On a more analytical note, Mister Scarlet's foe "The Hummer" can be considered an example of a "freakish flesh" villain for the same reason as two Dick Tracy villains, Mumbles and Gargles, because he makes weird sounds rather than having anything unusual about his physical appearance.