Text: The upward leaping orchestral figure anticipates the word, top, but the sung line does not, and at the punchline, But if Baby I'm the bottom, / You're the top, both Billy and Reno (I'm and You're) share a melodic line at the top of their respective ranges.
Entailment: Billy and Reno are musicians.
Contradiction: Billy and Reno have no musical ability.