Watch the T-Melt online guitar lesson by David Hamburger from New School Fingerstyle
As in tuna melt, that's right. As with most nicknames and colloquialisms, the origins of this title are best left shrouded in mystery. The steady thumb approach, and voicing the IV and V chords with the fifth in the bass, give things a low-rent, open-tuning sort of sound. The cool thing about the bass line walkup from open E to G is that your right hand thumb doesn't have to do any extra thinking - just keep hitting that low E string and your left hand will take care of the rest.