To say that someone "can't drink fog" is to say they're a lightweight at drinking.
It's history comes from many a Kerry man who has emerged from a pub after many pints, is suddenly hit by the air and immediately feels more drunk
Usually said after saying something smart or intelligent.
A longer version of the sentence is 'Up here for thinking, down there for dancing, out there for shaking and down here for making' Usually one would point to their head then feet for the shortened sentence. If lengthened one should then shake their hands and then point to their mid section while saying the last two things.