There's this stuff at GNC called "Red Line" or "XO Red Line" (something like that) which I want to try.
At the office, we have a ticking timebomb of a human here. The guy downs 4+ cans of Redbull while working. By 3pm, the dude is totally blitzed out of his brains ... very entertaining guy though. He said 1 "Red Line" gets him instantly to 3pm in one can