Linguistic humor, Beware of 'heard'

Source: Steven Pinker. 1994. The language instinct. Morrow. 188.
Beware of heard, a dreadful word
That looks like beard and sounds like bird,
And dead: it's said like bed, not bead—
For goodness' sake don't call it "deed"!
Watch out for meat and great and threat
(they rhyme with suite and straight and debt).