I do that sometimes with my mom's horse Jack, but I sure as heck don't lay down. Especially on the side where the legs are! I usually crouch and hug, get him to a more upright position, hop on, and tell him to get up. It's actually quite fun, not to mention dangerous.

Flying K Ranch
3 horses, 5 llamas, 3 rabbits, 1 dog, 1 cat, 2 geese, 15 ducks, 30+ chickens, and 1 crazy caretaker.