Super quick and easy to make. This will only take you less than an hour, even if you sew by hand. :)
(Sorry for the weird graphics >__<' I don't have PS on my laptop.)
1
Find an old pair of boxers (ask your brothers/dad/boyfriend/buy some) and wash it. They should be big & loose on you.
2
Decide on the length of your skirt. Pin the shaded parts to the inside. Cut the middle part where the legs/crotch meet.
3
Baste it. Fit it. Remove pins.
4
Hem it twice. Cut the extra fabric after the 2nd hem. And you're done! :)