If you know that “C” is for cookie and a purple vampire taught you how to count, you probably know the way to Sesame Street.

Now that the PBS children’s classic is turning 40, some of this season’s guest stars, including Jake Gyllenhaal, Christina Applegate, Kobe Bryant, Nancy O’Dell, and Cedric the Entertainer celebrate Sesame Street’s 40th Season by singing “Sunny Days.”