You can get an adapter that you plug into an earphone jack and it has two jacks in it.
You can buy these at Radio Shack or any computer or audio store (Best Buy, etc).
There's a website I follow called 1saleaday. It has one item for sale every day.
As it happens, they are selling a set of adapters today that includes a 2-1 earphone jack!
Go to this site:
http://www.1saleaday.com/
There are four items in the picture. The one in the lower right is the one you want. For the price, you could get all four. 8^)