Comment by pimterry

I would assume 'to dab your feet' i.e. quickly tap the ground with your foot when you're falling over, to rebalance. https://www.urbandictionary.com/define.php?term=dab.

I've mostly heard it in the context of technical mountain biking (where it's fairly common, but usually a sign of not quite getting through a section cleanly - you didn't actually fall off, but you couldn't keep your balance with your feet on the pedals).