The soda is probably for a direct sugar injection. I don’t drink caffeine often though and when I do, it makes me piss every 15 minutes. So I have just eaten 30 minutes before each of my sessions and kept a bottle of water. I’ve only been twice though, so these guys above me have way more time spent in a chair on the receiving end of a tattoo gun. They won’t steer you wrong.

Cheers,
-Rev