Hysterical!
This person heard two different accounts of their unborn child from two different people. The first was the OP’s nephew, who commented that he wanted a “boy-cheese sandwich,” though the baby in her tummy could have a “girl-cheese sandwich.” Pretty funny, but it would turn out that the OP was pregnant with a daughter!
Not long after, their cousin came up to her and commented that the baby in her tummy was hilarious. That might sound ridiculous, but this was long before the OP even told anyone she was pregnant! Were the nephew and cousin in cahoots? Alas, we may never know.