LOL! That wasn't the joke. If you look at the cover of issue #129 of the The Walking Dead comic, you will see two versions. The first version (the joke) has the words The Debut Of Daryl (or something to that effect) and has the image of a person (back facing the reader) with a crossbow in his belt.
The real cover has one of the characters from the comic being the real person there (and there is one that shows all the "changes" made to the joke cover). The character is question is really Dwight. The April Fool's joke was that Daryl was going to become a character in the comics. He's not. At least, not anytime soon. LOL!