Episode 4602 - Mucko Polo, Grouch Explorer HBO Premiere: Saturday January 16, 2016 PBS Premiere: Wednesday September 14, 2016 With Mucko Polo (Alan Cumming), Elmo, Abby, and Oscar use their five senses to explore and search for the grouchiest things on Sesame Street. Also featuring Grover finds a pyramid and Elmo the Musical-Guacamole. Brought to you by the letter E and the number 6. This episode features an all-new street story. If you saw "Mucko Polo, Grouch Explorer" please like this post and share your thoughts below.