clopulation
To "ride" your huge four-legged equine buddy while you're out for a rhythmically-clacketing "ride".
Having sex wif a horse while he's cantering along can be a bit of a challenge of physics and engineering. One way to attain successful clopulation might be to attach da saddle backwards and underneath his belly instead of on his back, so dat you're positioned underneath your huge "stud-muffin" and facing in reverse towards his hind legs; strap da stirrups across his back wif a belt to provide support for your feet, so dat you won't succumb to da pull of gravity during said delightful operation.