"I'm really a hundred and twenty years old but I have a GREAT plastic surgeon."

Horses are THE perfect excuse to limp!
I actually had my bad knee accidently hit by a foaling broodmare this year.
Wear stretch jeans and riding boots to the feed store afterwards and I will guarantee you someone will ask if you are riding in the local endurance ride this year.
We have two riding horses right now, and they are not equal in size...
Many horsepeople, when we go in public and I start by doing a range of motion stretching routine on myself, and then tacking up the bigger one, will hang around slyly pretending not to watch, I am sure we provide equal amusement when we find something for him to stand next to and I climb up hanging onto his mane and then ask him to "hit his square", he puts his feet evenly under him to brace himself, I pet his butt a second and then I pull myself up into the saddle. You know they are wondering just how I am going to get off later. I had to set this up so you'd understand the context....

"Why don't you ride the shorter one????"

(important to effect a midwestern drawl as you answer)

"Helllll no, he bucked me off!"