Horse auction

Santa and his son attended a horse auction with his father. Son was watching Santa as he moved from horse to horse, running his hands up and down the horses` legs, rump, and chest. After a few minutes, he asked, "Dad, why are you doing that?"
"Because I`m thinking of buying these horses."
Santa`s son looked worried and said, "Then I think we`d better hurry home right away!"
"Why?" Santa asked.
"Because the mailman stopped by yesterday, and I think he wants to buy Mom!"