(tutorial) extender slip

Recently I bought a skirt on the sale rack of Anthropologie. 
I really like it, but it is just a tiny bit too short and I feel a little uncomfortable wearing it.  I have a couple other skirts that rarely get worn for the same reason. 
As I was thinking about this skirt, I recalled seeing some cute slips that have a bottom edge that is made to be seen, poking out from under a dress or skirt.  I started brainstorming a way to make one, since the ones I have seen are $25+.
The thought of buying the silky slip material and making one from scratch didn’t sound very appealing…where would I even find that fabric, I have no idea… and then it came to me.  
Thrift store granny slips!  
So I snuck out the other afternoon and found a few at Salvation Army and they were 50% off! Bonus.  The good thing about granny slips from the thrift store is that they are super cheap, and can be made smaller VERY easily.  So what started out as a large sack, was easily transformed.  

And the options are endless!  My trim is just sewn on straight, but you could gather it for a ruffly affect, sew layers of smaller lace onto a strip of fabric, dye the lace, use more than one color of lace, use tulle, etc.  The only thing for sure is that you want the trim to be super wide, for when you bend over. 
(Don’t Laugh-I know this is a ridiculously unflattering picture)
OK, you can laugh 
but know your behind looks like this too when you bend over…. 
and who knows what is showing?  
Is this motivation enough to get sewing one of these babies?
**Oh, by the way, if you already have the trim ready to go, this is a 20 min project, max.  Just my style.**
Want to make one?

Half Slip
6″+ wide trim