Celebrities are constantly looking to diversify their portfolios. In Hollywood, being a singer or reality star doesn't mean you can't also launch a hair care business. Many stars have already ventured into makeup lines and other unexpected products like vodka-infused whipped cream, proving the sky is truly the limit. One of the latest trends A-listers have gravitated toward is energy drinks. With the global energy drink market valued at $79-$91 billion, there's no shortage of customers willing to pay - and likely even more so when a famous face is involved.