"Oh my, you are so clever!" she says laughing a bit at your joke. "It's great to be out here all alone with you!"
She then manages to move in such a way that one of her tits becomes exposed. You can't help but stare! She continues her teasing patter:
"And I'm so glad I got a male horse! Feeling it bucking between my legs as I drive it further and further towards the edge... of this moraine... is the most wonderful thing! And I like riding one that's so *big*!"
You say you can imagine that the horse really likes it!