Carbonated citrus juice with lotsa of sugar, caffeine, guaraná (just a marketing ploy since it's basically more caffeine) and taurine (which actually doesn't do jack, other than placebo effect at best).
If you need some that extra boost, try cola with coffee ice cubes.
Imagine there's a factory that works with medical chemicals for vitamins and supplements on one side. Next to it, there's a factory that produces glucose, dextrose and all that sweet crap. For no reason, both factories blow up and their contents slush together in the middle. The owners thinks it would be a shame to throw away, so they carbonate it and throw it into cans.
That's how monster tastes.
and I love the stuff......
Also, it's the sugar that makes it. The blue cans she got there are sugar free, but the taste is so horrid.
