When a group of musician get together, smoke an incredible amount of hash, and spontaneously play music without having any idea what direction anyone is going in musically. The end result is usually a song or noise. This is a method used by all the classic rockers of the last generation. It can be easily repeated without the bong, which i prefer.
"Hey I just started a band and we're going to do a shitload of covers until we are at Bong jamming Level."