She's a muscular boy,
A complete impossibility.

The story:

As a gauche teenager, I got up and sang this at my sister's wedding after having managed to steal and consume a pint of beer from my Dad when he was too drunk to notice. Unfortunately, a good few of my cousins as well as my sister caught onto my lyric. The error of my ways was pointed out to me later. I spent a weird five minutes trying to convince everyone that my lyric made sense (which it kind of does...first pop song about a transsexual).