When one is engaging in doggy style sex and the female looks back, she's giving the horse eye. This is because the man can only see one of her eyes, like a horse looking at its rider.
I was porking her doggy and she kept giving me the horse eye.
by The Reverend Floater August 25, 2004
To slyly check someone out by moving the eyes sharply to the side, but without moving the head.
Dude, I must look hot today...that guy just totally gave me the horse eye as we walked past!
by shmelody November 28, 2007