You and your friend enter a cave and you see a blue crystal, after touching it your friend gets the ability to swap your body's at will. They will probably use it to make you do boring things for them like wait for trains. And you got the unlucky side where you can't swap the body's at will and you just have to be in the body they give you. 

Jamko chooses to use this power more offen then you would like. Right after you both toutch the blue crystals you swap, and jamko can turn you back.