In my teenage years I stumbled in on my friend in the woods having sex with his girlfriend and I was invited to take part. When I walked in on them he was already mounted taking her doggy style. The sight of him sliding his hard pole in and out of her hairy pussy to me was electrifying.

We were probably about 18, she looked younger and was still partially dressed. He had her leaning against a tree with her blouse ripped open and her tits hanging out, her knickers were just pulled one side as he was on her.
I got an instant boner and took it out of my pants and asked her to stroke it for me, but it wasn't enough. I was aching to get him off her to let me get on and have my go on her.
It also frustrated me to watch him rodding her with her knickers still on.
I remember saying to him "You can't do her properly that way, let me rip them off".
I took my penknife out of my pocket, pulled the wet gusset clear of her ass and his cock and cut them off her.
I pleaded with him to get off her to let me get my turn, but he only taunted me by pulling slowly in and out of her and told me I'd have to wait until he finished on her.
It was a very a****listic scene, two cocks competing for one pussy. Two rutting stags competing for a doe. I was so randy to get my turn I couldn't hold off any more so I locked my arms around his waist and physically pulled him off her.
Then before he could double back I mounted her quickly.
She was fresh young filly with a hairy tight little cut and she bucked and squealed when she felt my balls on her hairy mound when I pumped my seed into her.