The choice is obvious

A banana is far more radioactive than a vodka soda, BECAUSE of the potassium content.
Choose wisely.

(Granted neither radiation level is significant as both are well below natural background levels. See: http://xkcd.com/radiation/ I couldn't stand myself after the above post as I hate that sort of fear mongering, but I couldn't help myself either.)

I might dehydrate you but at least I'm tasty