The idea for the game is you are a matador fighting various unicorns, the dev thread is here. The pose is from when the bull rushes past the matador and is trying to turn it's head to gore him. I'd link ref's but they tend to be violent/bloody.
It's a good thing that unicorns bleed rainbows and glitter. 
Slightly awkward pose, but I really like this. Something about the colours is quite appealing to me.
@Rayovatron
I did use a ref, but it was more like this: grossly muscled bull. Did you mean out of proportion compared to the body/front legs?
@Level 1
Yeah, that is the part I'm least happy with. I might try re-working the shoulder muscle and the front left leg.
Might want to work on the ront legs a bit, they seem to be a bit weird, and the muscle shading feels as if it's not smooth enough
He's such a bulli. 
Got anymore details on the game you're working on?
Saw this on Tigsource. Really good and the muscles are really well done