And now I get it. They got me

You’re confused, and therefore, according to the post, gay.

Serious answer: the joke is that the sentence leads to believe that something related to the queerness will follow, but the apple is unrelated to that, leading to confusion. This confuses all people and therefore also gay people, making the statement true. Alsp: The other commenter is actually not right because gay people are a subset of the confused people. Your confusion is not enough to deduct you being gay. You could even be straight for all we know!