This would have to be after I'm dead and gone. I'd like to be posthumously famous for spending my (secret) multi million pound fortune anonymously on good causes. I would've spent my life leaving bundles of cash in charity shops and old people's homes, paying for hospital wings and expensive equipment in secret, buying huge houses and posting the keys to children's charities, buying huge tracts of land and constructing adventure playgrounds for local kids, paying off the debts of people who deserved it and anything else I could think of, but without anyone knowing it was me!!
And also for replacing the government with my 6 year old's class at school for a laugh, and finding that everyone preferred it that way.
If someone could send me the millions I'll be needing, I can start straightaway....!