I don't know if this has already been posted but...there's been at least 3-4 Sesame Street references on "Family Guy".
Season 2 - The Griffin family goes to New York City for Chris to be an artist. Peter is angry for Meg doesn't have any talent. But she can do bird calls. She does 2 or 3 and then suddenly, a gawkey yellow bird walks up. Yes, it's Big Bird, but the rings around his legs aren't pink, they're a faded green. The voice is of course, Seth Macfarlene who in which does the voice of Peter, Brian, Stewie, Quagmire, and Tom Tucker. He does the Big Bird voice, although it sounds more like Quagmire.