Sometimes dealers can get funny when you try to ask for a discount that you know is possible, but they might not like do. Post your best ones here from your attempted hacks!
Inspired by this:
Here is one of my best to kick it off, suggesting they only had 6% to work with and that I could only find a deal like what I asked for on a car that was totaled and repaired. (I was asking for 10% on a very well aged X3M):