A person typically has hair under a pony tail. Under a pony's tail is their anus which is where they defecate from.
Pony
Looks like the tail of a well-groomed pony.
ride a pony
naomi pony
pony tail
it looks like a horses tail, obviously.
the Chinese king had a pony tail too
brushing the mane and tail of your horse/pony
tail
up in a pony tail
put it in a pony tail