I used to love the Yip-Yip martians on Sesame Street when I was a young lad. A couple months ago, I got to animate one of them made out of construction paper (yip-yippee as ever). It was a blast making the animated characters and backgrounds for Abby & Elmo's "I Spy Blue", which is now out of Sesame Street's YouTube channel. https://www.youtube.com/user/SesameStreet