Purchase a small army and overthrow a small island just because i can,where id do "dr moreau"esqe experiments then take over the world with my steroid taking flying superchimps,rename this place "planet of the apes" and then retire in hawaii!
My first reaction was to say "buy champagne".
However, two verry good friends of mine (husband & wife) both have cancer and are having their house repossessed. It would give me a great deal of pleasure to sort out their financial problems.
I'd give my MIL some cash as she's been bringing up her 4 grand kids for the last 10 years as the mother 'doesn't want them' but still gets all the benefits and family allowance for them.
pay my dads mortgage of, pay my debts off, give my mate enough money so she has an escape route if she needs to take it. and party whilst travelling the world
I would buy a big house with a huge kitchen and then invite frends round to dinner parties as I love to cook. I would pay someone to do the washing up and clean up after me though.