I've somehow managed to stumble upon a Blues guitarist I like, Aynsley Lister, and have been listening to his music all day now, and while I normally don't listen to or play a lot of Blues (I'm more of a 60's-80's Hard Rock kind of person...), I must admit that this guy is pretty good. I've got one question, though. In one of his songs, "Straight Talkin' Woman", he plays something that sounds really cool about two and a half minute into the song, and I think I've heard it in some ZZ Top songs as well before it. I just have no idea how exactly it's done. I've linked the video below, in hopes that someone can tell me how it's done.

http://www.youtube.com/watch?v=oSfeX-im3RQ (from 2:32 to 2:40, roughly)