Answer:
Lol, I hope this isn't a thing that happened. But now I'm intrigued tell me how it turns out and I would love to hear the full story lol.
Step-by-step explanation:
Dear (Uncle nickname),
Recently there was a problem with my school involving me/ that doesn't involve me and/but I was asked to pay an unreasonable amount of money. You know how clumsy/careless. (insert cute or funny childhood story he was apart of that will remind him of you being clumsy). I don't think I can pay the full amount as it is a scary amount of money. If you could help me out I would be eternally grateful.
Thank you,
(Insert your nickname given by said uncle)