Ninjas?

My wife and I are pregnant. This is so cool! Anyway, we have both hoped for twins so we can have two kids in one pregnancy and then call it quits. Well, the ultrasounds don't look good: just one kid in there...

UNLESS: how cool would it be if we had twins after all and we didn't see the other one because it was a ninja? Ninjas are born that way, right? Right? 

Oh, well. I can wish. Seriously, I hope it's a girl. We shall see.