Little johnny boards his school bus and sits right behind the driver.
He starts to sing a weird song:?
"Had my dad been a dog, my mom been a bitch; I'd have been a puppy".
"Had my dad been a horse, my mom been a mare; I'd have been a colt".?
"Had my dad been a tiger, my mom been a tigress; I'd have been a cub"
.......... and so on.
The driver who is constantly getting irritated by his dumb song asks him:
"What if your dad had been a gay and your mom had been a lesbian?"?
Little johnny replies: "Well then, I would have been a bus-driver".