Just my usual note that, contrary to what one might think, a small energy shot such as 5-Hour Energy has twice as much caffeine as a standard Red Bull or Monster -- and is a lot easier to get down fast. Also, as has been noted, coffee does the job for many, and some find benefit from taking a taurine pill along with the coffee. Finally, any caffeinated drink seems to work better if you have been off of caffeine for a while (e.g., before your cycle starts).