Your brother who spends money as quickly as he gets it, always wearing new clothes and taking friends out for expensive dinners? You might call him a wastrel, meaning he spends his money foolishly.
The word wastrel looks and sounds like waste, which means, as a verb, "to spend or use carelessly" — as a noun, it's the thing that is not used effectively. A wastrel is someone who tends to waste things, careless with anything from money to time, and everything else, too. You can tell wastrels by behavior like running the water while brushing their teeth or spending every dime they have on ice cream and luxurious sweaters.