*scratches head* I Don’t Get It

My Wonder Woman isn’t particularly fond of a song I sometimes sing. Maybe it’s because it features her cat. . .

To the tune of “Muhammad Ali” (Float Like A Butterfly, Sting Like a Bee)

Catrina, Catrina the cat,
Floats like a butterball
‘Cos she is fat. . .

I don’t get it. What’s the problem?