I object to The Beetles’ “Letter B” very strongly as Jim Henson’s thinly veiled apologia for the Khmer Rouge:

♪♫
“When I find I can’t remember
What comes after ‘A’
And be-fore ‘C’,
My mother always whispers: Letter B!
Letter B, letter B, letter B, letter B!
The buh-buh-buh of B-words, letter B!”
♪♫

Sesame Street: The Beetles - Letter B