For all of the musical parodies that Sesame Street produced, very few of them resembled the original song enough to warrant legal action.
In the early 1980s, the Children’s Television Workshop (CTW) was sued for $5.5 million by the Northern Songs, owners of the Beatles catalogue, who said the song “Letter B”, performed by the Sesame Street Beetles, had the unfortunate distinction of being too similar to the original “Let It Be.”
However (thankfully), before the case went to trial, Michael Jackson purchased the Beatles catalog. Mike, also, decided not to pursue legal action, and CTW was only fined $50, which songwriter Christopher Cerf paid out of his own pocket.
*Words sourced at Tough Pigs + Mental Floss; fact-checked & reworded by yours truly.