I have an issue with loud chewing and couldn't figure out how to get my oldest to stop share the noise of every dinner bite.
In the van one day I just said "Zoe, I'll give you 5 dollars" and she got excited. "You have the $5, but I won't give it to you until the end of the month. Each time I ask you to stop chewing loudly $.25 will be taken from the $5. You can either end the month with all of it or much less. Sound good?" She happily agreed and her sister wanted in, but we went with nose picking as that was her issue.
At the end of the month I was amazed at how well this worked. I would always give Zoe a warning first as I needed her to not lose all the money and make it all useless, but only needed to deduct $.25 once from her and $0.00 from Shiloh.
I didn't think it would go so well so I've used it for other things since then. It's like a game to them with a reward. We keep it light and fun and I get to have more peace in my life:)