Watch the Thumbthing 2 online guitar lesson by Rich Maloof from Guitar 201: Breakthroughs
Our progression for this exercise includes four chords: G B C A. Keep that thumb glued to the bass — that is the thumb’s only job, to hit those bass notes. Note how the pattern alternates between plucking all at once and then separating the bass (thumb) from the upper notes (fingers). It can take a little while to get this together, but it feels great when you do.