Fighting with your friends in the backyard is not sparring. That is what's known as horseplay, tomfoolery, or shenanigans. It's also a good way to get someone hurt. My advice would be that you stop beating each other up and join a real gym. Failing that, get some mouthguards, some cups, and facepunch away.
"I don't want them to like me, because when I'm in the ring, punches fly to the face. It is not a tenderness time. I am not falling in love. And he knows that when the fight starts I am kicking faces."
- Wanderlei Silva