Today marks the 41st anniversary of the first broadcast of Sesame Street. Happy Birthday Sesame Street! Over the years the classic PBS show has taught children innumerable life lessons: muppets that live in garbage cans are grouchy, giant yellow birds have surprisingly high voices, anybody/thing named "Grover" is a little dim. But while the program has undoubtedly been a positive educational resource in its four decades, some of its guest hosts haven't exactly been perfect role models. From Mel Gibson to Chris Brown to Richard Pryor (R.I.P.), we take a look at a few of Sesame Street's past friends who definitely won't be invited back for the birthday party.