Yip! Yip! Okay, so Sesame Street may not be the first thing you think of when you think of Halloween, or even geek crafts. Fine, but you have to admit these costumes are pretty awesome! Traci Lawson posted this great Yip Yip Costume with full instructons on her blog dedicated to children’s video games. Even if you don’t see yourself making your own Yip Yip Costume, I still suggest checking the instructional blog out, so you can see a video of Traci and her friend Yip Yipping in New York City.