Pony tails vs. pig tails

[warcat]

N and I were in the car driving home from a birthday party and N asked me why pigtails aren't called pony tails.  I told her it didn't really make sense to me but that a ponytail is always just one in the back of the head and a pigtail is always two.  So she said why can't there be a horses bottom on one side of your head, and another one on the other side and the two horses bottoms were together.

And that just made me snicker.