I have stated in another message that I think humping is a Yorkie thing.
My yorkie hops on the back of my larger dog's back and humps like there is no tomorrow. It is embarrassing when other people are around. First time someone witness the humping they are like.....I didn't know girl dogs do that!!! I say, will it seems girl yorkies do!!
Every time she does it I make her stop, but she want quit.
Thank goodness the dog is the only thing she humps.