Originally from my blog
Here's a simple little clothing hack I devised for fixing when your drawstring elastic waistband (or hoodie sweatshirt cord things) come out of the loop they're supposed to stay in. When this first happened to my beloved old sweatshirt, first I spent a good deal of time grumbling at myself for not tying the ends properly in bigger knots to keep them from escaping into the fabric. This act alone will make the rest of this advice a moot point! But if you're like me and made this mistake...twice...with a pair of gym shorts later...help is on the way! From yourself.
Clothing plus lost band
Step 1: Preparing the Pen
The trick was to find a needle-like object that is pointy, skinny, and flexible. After ransacking my apartment, I stumbled upon the center ink thing from my ballpoint pen. I removed it from the pen and fastened it to the elastic with tightly wound scotch tape.
Step 2: Threading It
It's important to move the pen/elastic combo slowly, and to know when to push against the fabric and when to ease up. Once you begin to trace the path around the waistband, beware of snags where the fabric leaves only a small space between the stitching for the drawstring, and also of poking through the fabric instead of following the elastic band path.
Step 3: Bunching
I found that a bunching technique works pretty well. With one hand I pushed the fabric over the ballpoint, and used the other hand to pull it through.
Step 4: And Out the Other Side
Eventually you should come out the other end again. Hooray!
Step 5: Preventative Measures
Be sure to tie those big knots in the end that you were too lazy to do in the first place. And enjoy your old clothes all over again.