There must be quite a few older songs that can give rise to unintended double entendres arising from the changing predominant meaning of the word 'gay'. But this must be one of the most uncannily funny examples thereof. The song is about trying to feign indifference to a lost love. However desperate a strategy for doing so it would be for a 'straight' person to pretend to be gay in the dominant modern meaning of the word, the thought happens to have just the logical coherence needed to make the song especially funny in that regard, possibly even to make some desperate lovelorn person try just that strategy.