"... there will be a demonstration on how to crochet plastic grocery sacks into handbags, swimsuits and beachwear."
There's a page here (with pictures) about doing just that: http://www.marloscrochetcorner.com/Plastic%20Bag%20tote.html
Wow I wish they would have shown pics with this! Last year I was elected to crochet a faux designer outfit for a recycling contest my sons school was in! I made the wrap skirt and jacket from recycled black garbage bags and the tank top from yellow store bags that groceries had come home in and even did a purse in another stores white bags! It was soooo cute!! :-)