Also any beverage with lots of sugar, or with any amount of alcohol, requires the body use up water to process it. The coldness quenches thirst temporarily because it gets interpreted as "cold water," but then you get thirstier as the stuff is digested. So you should increase your actual water intake when drinking those things, but do it carefully because it will also increase the effects of their other psychoactive components (and you could accidentally OD).
Another common form of geek fuel around here is Skittles candy, the little fruity things with the "s" on them. (Also useful at parties, to mix with M&Ms in a bowl, and then you can call the mix "S&Ms"

. I can eat a handful of those and woo-hoo, instant energy!
Dosage control is the key to avoiding blood-sugar crashes. Just eat (or drink) enough (candy, stimulant beverages, etc.) to perk you up a little, not put you in orbit.
When it comes to playing with your brain (and brains after all are fun to play with), the key is to learn to observe subtle changes, and work with them carefully. A little goes a long way.