It's very embarrasing. He's a Golden Retriever, 2 and a half, castrated. He humps other dogs he meets out on walks, and our other dog, a spayed Labrador bitch. He doesn't do it in the house, or to objects or people. Only when he's out, this includes playing in the garden with our other dog. I've just put it down to excitement, and perhaps dominance. Anyone else had similar with their dog? Any tips on correcting it? I'm finding that shouting "stop that you dirty bugger" at him isn't proving very effective.