Guitar Headphones Answered

Im in need of help.
My friend has a bass guitar but no amp.
And instead of buying one he asked me to figure out a way to let him just plug in his headphones.
After glancing around at all the instructables for portable guitar amps I hadnt seen one for just plugging in headphones.
SO, I'm asking here in hopes of someone else knowing where an instructable is for this, because I can't find one.