A thumper!

Walk without rhythm, or Shai Hulud will get you!

Darwin actually wrote about this in "The formation of vegetable mould through the action of worms with observation on their habits" in 1881. Tinbergen also wrote about this when describing a foot stomping technique used by the herring gull to harvest worms. And if that wasn't enough, turtles do it too!
neat stuff.

edit- Oh, and major hypotheses for why worms do this:
1) To avoid predatory moles signaling with seismic vibration or digging.
2) To avoid drowning during a rainstorm, or to disperse on the surface when it is still wet from rain.

I'm sure glan it's "not in MY blood" to do this kind of work! - But good for them

Please tell me this guy has a facebook page.