'50-Cent' is a term used to describe someone (mainly a rich person) who spends their money loosely or excessively without caring about the expenses.
They usually spend their money on extrememly trivial things or buy luxuries that they already own.
Look at that guy there buying a bottle water near the drinking fountain, he must think he's 50-Cent or something...
Look at Andrew, buying another pair of Nikes when he already has 3, what is he 50-Cent or something?!