When coding, I have one of three things, depending on my energy level and temperature:
Low energy, cold = hot chocolate (1 teaspoon of whichever drinking chocolate is in the cupboard)
Low/medium energy, not cold = orange/lemon/berry squash, 1:8 - 1:10 dilution (yes, that’s half or a bit under half the recommended amount of squash, because it’s light enough for the flavour to still come through)
Otherwise = tap water.
Drinking a mug of hot chocolate typically converts LOW Energy to HIGH Energy for 2-4 hours, which I have to be careful about, because if I’m in HIGH Energy mode I seem not to be able to concentrate on coding. However, I can do other parts of IF, such as writing, and it’s outright beneficial for creating music because I don’t make music very well unless I’m in at least MEDIUM Energy. (Art doesn’t seem to be connected with energy level for me). Drinking squash in MEDIUM energy may do the same, or it may not - I’ve not learned the pattern, and it’s more likely to either convert LOW Energy to MEDIUM Energy, or leave me at the same MEDIUM level.
Apart from the hot chocolate, if I’m going to have caffeine, it’ll be in chocolate bars (preference for dark chocolate, fruit enclosures preferred, but in reality I’m not that picky) or chocolate biscuits (bourbons, dark chocolate digestives or chocolate creams). This has the twin benefits of increasing caffeine at a rate I can more easily control, and doing so more slowly (thus giving me time to wrap up what I was doing at the previous Energy level). My computer area attests that I eat quite a few of these, although sometimes I don’t have any caffeine sources. (It also has my drink on a separate table to the computer, so if I did knock it over, the computer shouldn’t be affected).
I don’t drink alcohol at all; don’t like the taste.
I can and sometimes do write first thing in the morning before I’ve consumed anything whatsoever; my brain starts up pretty much immediately for writing purposes, though actual coding seems to go best in the evenings.