Go to Jolly's as either Banjo and Kazooie or just Kazooie alone. Jump into the fireplace until you have only one honeycomb (don't kill yourself in the fire!). Now, activate Jolly's jukebox and then turn it off to position yourself correctly. Fire a clockwork egg behind you, put it behind Banjo's feet and hold B. The egg will explode and Banjo will die... but he'll get back up again to use the jukebox. Turn off the jukebox and weird stuff happens.