What should I do with this dog (details inside)

You know it was trying to have sex with your leg, right?

Unlike cats, which are the pinnacle of biological evolution and an ontologically perfect species worthy of worship—dogs are kind of dumb.

Don’t try to understand its change in mood. It didn’t trust you, and now it does but maybe think its your bitch (literally).

So could you ask the dogs owner to introduce you? I don’t think all dogs are dumb at all, so a treat and the owner giving you his/her name would be a great start.
Also animals sense fear, you must control yourself, and make friends. If he got close and didn’t snap or bite, you’re likely on it’s ‘undecided’ list still. :)

Dogs often have to warm up to you. Many of the most loud, obnoxious pups can be the sweetest cuddle bugs once they feel safe with you. If it’s not “fixed” beware that they may indeed want to copulate with any of your extremities. Some dogs are wicked smart and can pick up on very subtle mannerisms in people. Cats on the other hand, while having personality, are relatively stupid compared to dogs.

Leg humping – Nice.

So this mutt goes from threating to bite your face off, to treating you like girlfriend material.

So very human.

Just keep your distance Mimi. This is an animal control problem, not a life crisis.

Ha. No, your dad is wrong. This is not friendly dog behaviour. The dog was mounting your leg (or attempting to). While this happens when dogs are sexually aroused, they also frequently use the action as a way to control others. Usually when they’re feeling very excited or anxious. For example, I’ve seen many dogs mount younger pups who are playing rambunctiously. When the young ones settle down, the mounting attempts cease.

So, “your” dog is still worried about your presence. He’s not being friendly, but it does sound like the aggressive displays have decreased. I think at this point, you should start carrying a handful of dog treats around. Maybe leave them with your motorcycle. The next time the dog approaches, toss the treats to him. This will distract him if he’s thinking about mounting you. At the same time, he’ll learn to associate you with good things – which will lower his anxiety, and, in turn, the drive to mount.

You don’t have to feel weird about this dog displaying “sexual” behaviour. He knows you’re a human and he doesn’t feel attracted to you. Even among dogs, mounting is often not sexual at all. Dogs are very social and like humans, they can understand context.

Mounting behavior is usually about domination. I’m friends with 2 Boston Terriers, brother and sister, who I’ve known since they were 8 weeks old. In the beginning, the boy was more assertive. Now, at about 20 months, the girl will often mount the boy, telling him that she’s in charge.Oddly enough, he’s jealous any time a human comes around and nips and growly-barks at her, telling her he’s in charge, so I guess they take turns.

I really like the idea of keeping treats with your bike (if it’s in a closed space) or bringing them with you when you go somewhere. But like @longgone says, toss him the treats; I wouldn’t hold them out to him, at least, not at this point.

No one assumes “the dog grabbed my leg” to mean the dog held my leg in its teeth, my own reaction to hearing that a dog “grabbed” anything. A “soft mouthed” dog is worth its weight in gold to a hunter.

Ok the climb thing, which I missed, probably clinches the fact that the poor dog is simply smitten. Once again the timeless tragedy of unrequited love. Sigh….

Thank you everyone for answering. I like how @Kropotkin and @Blackwater_Park have two different opinions about dog’s intelligence :) And to be honest I was feeling uncomfortable with the sudden humping there that I didn’t know how to react. I may try the dog treat and see if it could get to a good result.