Falling off the wagon is a euphemism for a reformed alcoholic that starts drinking again. It is a useful parody of what happens when one falls back under the influence of the ego’s wants desires, and judgements.
You wake up the next day and go oh my god. Not again!
Well brush yourself off and give yourself renewed determination to control your perceptual focus and not to give up self control to the ego, aka the perceptual booze, again. ommmmmm
Hold your perceiving focus at your heart and get it out of your head.