Alternately you can keep the two skeins or balls in a plastic grocery bag, when you get a few twists pick the bag up by the handles and spin it so it untwist the two strands of yarn. It will wrap the about the handles but they will fall out right when you let go of the bag. Best to take the first twist slowly so you know your spin is in the right direction.
If you spin it too much and it starts to twist up again, no worries! You are just ahead of the game and as work the twist you make will untwist the strands from your yarn bag.