Re: "Buying" a ticket is a classic money laundry method.
Or you could put $4000 into a London bank and have a clean $4000.
I'm not sure why you got a downvote for this, apart from assuming that a bank wouldn't charge as many fees as possible on any transaction. For what it's worth HSBC were charging approximately 20% to launder money.
Of course, HSBC got caught and got fined $1.9 billion, which sounds harsh, until you realise that all charges were dropped in exchange for just five weeks worth of profits. Too big to fail and too big to jail.