The further you advance into the neverending pit of "the jam" the more you can telepathically communicate with your fellow musicians. You will start a jam and you will get into a "groove". Your fellow musician friends will experience the same thing. The bass and drums are usually the basis of the groove. Now jamming is just like talking, so you send messages to your fellow musicians that you will be changing key, or going into a song or standard. For example, I was jamming with some cats the other day, and we were in Bb and I felt the chicken coming on, so I started playing the bassline, after two measures it goes silent and I'm playing the bassline, then it picks up again and we're suddenly in the chicken. Next thing you know, we're jamming on the super mario theme song. Then inspector gadget! We ended it on Mercy, Mercy, Mercy. Good stuff that jamming is.