Yep it's a horse butt.
The story here is I work at a race track walking horses and my boss was talking today about doing a new t-shirt to get back at a guy who jerked him around last year. He named a horse after this guy, called her 'B A Hole Auger', (think about it) and did a shirt last year getting back at him. While talking about what to do this year I did a quick sketch he liked, then decided I could do a better version at home and send it to him. And this is it, maybe it will be a t-shirt later. Weeeeeee.
This is not fetish, although I know some who like the horsie butty, but I like how it came out, especially the face.
Oh well, back to my harder projects.
*Edit note, boss wanted the name branded on the ass so branded it be*
PS I said it doesn't contain mature content, am I right? Does a funny horsie anus count as mature?
Guess I'll find out.