I actually was part of a band where this happened, frequently. The one guitarist, who was, you guessed it, the inferior one musically, would always be screwing with some riff or other nonsense while the rest of us would be trying to talk to one another to discuss song bits, vocals, etc. Since I was behind the kit sitting down it was hard for me to do anything about the noise so the bass player would just walk over and either unplug the guitar or turn his volume knob all the way down. That got his attention.Now we were all pretty close friends so laughter would usually follow but the point was made...shut the heck up!!!Have a word and if he continues to play when the band's discussing band matters simply turn his amp off.