Deal escalates - to a threesome with a mega finale

I had a cool idea with my teen girlfriend and then this happens! I had an old couch that someone wanted to pick up for very little money. But on the day of the viewing he didn't like this and that and didn't want to pay the price. After a lot of back and forth, something occurred to me! I'll just say this much: he got everything he could out of it and I would never have thought that this threesome could get so hot!