I can't crochet, but I want one! How to Crochet a Yip Yip Alien. The Yip-Yips are characters from vintage Sesame Street. They're not as well known as many other Muppets, but they're some of the funniest characters, and also one of the simplest shapes. The originals were little more than a tube of furry fabric with eyeballs and antennae. If you crochet, it's easy to make your own miniature yip-yip.