I've never heard the phrase on its own - except in the eponymous Osmonds number - but you do get 'wild horses' in the phrase 'wild horses couldn't drag me away', as in the Rolling Stones song, 'Wild, Wild Horses'.
"Crazy horse" is a name given to someone who runs a lot when it isn't necessary, just like a crazy horse. 70s Liverpool legend Emlyn Hughes was given this nickname as a reference to the ground he covered during a football match.