Blue Thingy?

I spent several hours browsing in our local Peddlers Mall, a large building full of booths rented by vendors selling just about anything. Lots of flea market type items. While going through a stack of linens (where I found a lovely linen/lace hanky for .50) I came across this:



The seller had only marked the tag as "Blue Thing .50" At first glance of course I thought napkin or doily. It's made of a stiff linen fabric. But after playing with it, I discovered it did this:

OK I know in my years of perusing woman's craft magazines, or mail order catalogs, I have seen this, but right now I am clueless as to what it is for! I am sure there is someone out there in blogland that knows, however, that someone probably is not reading my blog LOL.

However, if you think you know it's purpose in life, or better yet, have an internet link to an explanation, please leave me a comment with that information. For once in my life, I am not going to just google it, I do not even want to think what hits I would get for a 'blue thing' search.

CW