A ginger kid (also known as a durl). Simply Red Muff spelled backwards. Usually the brunt of most every joke.
(when your friend is nicknamed ffumder) "I heard this chick was about to go down on ffumder, but then she saw his red muff and decided to go home. ffumder, that fucking durl."
DURL is an acronym for Dumb Ugly Red Loser. Basically any ginger falls into this category, as it's extremely difficult to be just a DUR (if your Dumb, Ugly and Red, you are also a loser). Actually, if you red, you're ugly, in which case you're a loser. So if you're a ginger, you're a Durl.
Hey Shaun White, You fucking durl.
Hey Carrot Top, you fucking durl.
Hey Matt Friedman, fucking durl.