Sesame Street® 1st Birthday Mylar Balloon. This first birthday balloon is brought to you by the number “1”! Elmo, Big Bird and Cookie Monster will help make your boy or girl's first birthday party an extra special celebration! Featuring Sesame Street's favorite characters, this Sesame Street® 1st Birthday Mylar Balloon is perfect for decorating a party tables and surprising the birthday child. 18" Sesame Workshop ©, Sesame Street © and associated characters, trademarks and design elements are owned and licensed by Sesame Workshop. © 2007 Sesame Workshop. All Rights Reserved.