There are plenty of real world situations where you can negotiate prices.

Thank you, I hadn't thought properly about that. I was avoiding all those situations. Doing actual negotiations for small stakes is an excellent plan. It's not quite perfect. It doesn't give very good feedback, since I don't get any information about what they would have been willing to settle for if I were a better negotiator.

When you want some form of interacting with your friends, you could bet with them frequently. Betting means that you can negotiate the odds.

I'm interested in this, but my friends really don't like to do it. They also don't want to play games with me for money.

I think part of the reason they don't want to is that they think I will win. But I think I would win less if we played for money!