The Yip Yips (also known as the Martians or Aliens) are characters on the American educational children's television show Sesame Street. They are puppets depicting alien visitors from Mars. with notable physical features such as squid-like tentacles, large eyes, and antennae. Built by Caroly Wilcox, they are "Yip Yipped" by multiple Muppeteers including Jim Henson, Jerry Nelson, Richard Hunt, Martin P. Robinson, and Kevin Clash. The puppets have a very simple design, controlled entirely by two rods (one for the body and eyes, the other for the front of the mouth). This allows their entire bodies to be seen on camera, appearing to float in the air. The Yip Yips appear by materialising into a room, always saying "Yip-yip-yip-yip... Uh-huh" upon arrival. As they come across common objects they are foreign to them, the Yip Yips consult a book they call "Earth book". When they fail to 'correctly' interact with an object of Earth even after consulting their book, they are known to say "nope nope nope". Another common trait of the Yip Yips is that when frightened, they cover their face with the lower part of their jaw while making a "goom" noise. Skits 1972: Phone discovery by the Yip Yips 1972: Grandfather clock discovery by the Yip Yips 1978: Ernie wakes up and is unable to find Bert. Ernie imagines that the Martians appeared in the middle of the night and asked Bert to join them in outer space. Bert then enters the room and informs Ernie that he was only in the kitchen making oatmeal. Bert leaves the room and the Martians appear in exactly the way that Ernie had imagined. When Ernie yells to Bert asking what they should do about the visitors, Bert does not believe his story and replies, "Ask them if they want any oatmeal," to which they enthusiastically agree. 1979: Radio discovery by the Yip Yips 1986: Luis walks away from his computer briefly, and the Yip Yips visit during that time and experiment with pressing buttons on the computer. Luis comes back to find that his computer has been changed by someone. Later in the show, the Yip Yips come back and leave a flower on the keyboard, which Luis discovers. 1987: A Yip Yip contributes its voice to the Old MacDonald Cantata along with three Honkers, a Dinger, and Oscar's pet elephant Fluffy. 1988: The Yip Yips observe Luis and