My beagle Loki is a female and she humps Samson sometimes. He'll be laying down chewing his bone and she'll mount him and hump his head. She's crazy, she'll growl at him if he tries to get up, it's kind of funny. Normally Sam's not much of a humper, when he was a baby he would hump this little stuffed pig he had but not anymore. He does hump my friends male german shepherd Smokey who's ~ 8 months. Over the years Samson has become "scrappy" with males, he acts like a total bully (no pun intended LOL), he becomes very vocal, not like an aggressive growl just being very vocal. I think Samson knows Smokey is still a baby so he isn't a threat but still a male and feels the need to asert his dominance. And when he sees Smokey it's constant, I am constantly dragging him off poor Smokey