None. Horses are not known to use operating systems nor computers for that matter.
Hay,I thought you knew horses couldn't speak!
No one can ever know.
A terror-phone.
Amiigo
Matthew McConaug-hay
Helephino.
Someone stepped on the mouse.
Because they heard he's a web developer.
Oh it doesn't really matter.
It doesn't matter how many. They just compliment it and get mad when it won't screw. Edit: Credits to Drougen for making it better.
Pulp Fiction
Women!
Unix