Watch the Droning Application online guitar lesson by Stu Hamm from Stu Hamm U: Slap Bass

One of the most simple ways to use open strings while slapping and popping is to play an open note with your finger with the popping motion and fret the same note on the next string and slap it with your thumb. The sound of the same note being struck in two different spots creates a nice "out of phase" sound, similar to a technique that sax players use.