If your male dog frequently humps other males, don’t worry—it isn’t that odd. Lots of male dogs do this, even after they’ve been neutered, to establish their dominance.
If you just introduced a new dog into your household, your older pet will want to show newbie right away who’s the alpha male. Or if a stray dog tries to enter your yard, he may feel the same instinct. It’s best to interrupt this behavior right away if you notice aggression so it doesn’t lead to a dog fight.
If you’re scared to physically remove the mounting dog, spray him with a water bottle or make a sudden loud noise.
You just might see a little humping. In this case, it’s perfectly OK for them to play with each other. Just keep an eye out to be sure neither gets too feisty so nobody will get hurt.