Watch the Tuesday's Just As Bad online guitar lesson by Brad Carlton from Chord Studies: Slow Blues Progressions Vol. 1

In this example we'll play a slow blues in the key of G that is based around the song "Stormy Monday", originally written and recorded by T-Bone Walker in the west-coast blues style. Notice that in the ninth measure you have a suspended fourth which creates an open yet dissonant sound, and in measure twelve you have a D augmented chord, meaning the fifth of the chord is sharpened or "augmented".