While you can use a 3.5mm splitter to share your music by adding a second set of earbuds,
There is anew product called Skunk Juice Earbuds

At the end of this connector is another magnet that allows you to attach a second or even third set of earbuds.

A additional benefit of using the magnetic connector is safety.
If you are tired of getting your earbud wires caught on objects and getting your earbuds ripped out of your ears.
Skunk Juice Earbuds