Why is caffeïne a programmers best friend?

Caffeine is not necessarily a chemical that introduces extra energy in to ones system - that is the job of your carbohydrates. It instead helps focus your mind on the task at hand, rather than be jumping from one thing to another (which always happens to me when programming because I will be writing something and go "OH MAH GOD I could do this too!" and sometimes drop what I was doing to write that down and develop the idea further). That it does this isn't necessarily something that you would notice easily, but scientific studies have shown this to be the case, as well as its effect having been noticed enough in common use that it has become known for the property of energy (I would say that could be to do with the fact that people associate being alert with being focused).

Yeah I definitely don't NEED coffee to program. Honestly for me its just a comfort to have a cup of coffee and sip on it while I work. And I really think its a psychological thing, like placebo. Merely having the coffee makes me feel more focused, probably even I get decaf instead.

As for pizza, pizza just rocks. It's concentrated calories! Usually when I eat pizza though I am watching a movie or hanging out, not programming. But that's probably because I do my programming in the day usually.

Yeah, energy drinks contain chemicals like Taurine which are much more potent than Caffeine, as well as, like you said, LOADS of sugar. That said, I have never been affected by energy drinks significantly, they never make me feel more awake, I just sort of don't sleep for a while after having one, so if it weren't for the fact the taste of most of them displeases my tastebuds I would probably be better off using them at night, because I can be super productive in the 23:00 - 03:00 period. Of course, doesn't stop me from being nackered in the morning, which can be quite bad when I have 7-8 hours of college the day after.