That's Bring Your Own Bag, an earth friendly grocery bag.  Quite a few years ago I acquired about 20 cloth grocery bags from a local grocery store, IGA.  The bags were subsequently stolen from my car (Ya, they'll take anything not nailed down.) and when the thief realized it was just a cloth bag full of more cloth bags he tossed them in the garbage can in the park across the street where my kids happened to find them.  Of course I had to wash them and to my dismay they shrank to half their original size.  Being too small for my needs I gave them away and acquired another 20 or so cloth grocery bags and wrote my name and phone number on each one with a grease pencil.  I have kept them in the back of my car 365 days a year and I'm sure all of the Safeway cashiers refer to me as, "OMG!  It's that lady with those awful bags.  Please, please, please don't stop at my checkout."  These bags are rather difficult to pack as they don't stand up by themselves like paper bags and they don't fit on the little metal rack like the plastic bags.  I remember one occasion when a young box-girl was reprimanded for arguing with the cashier over who was going to work the cash register and who was going to get stuck packing my bags.  I never washed these bags due to the shrinkage.  They have now become more than a little soiled and the grease pencilings have faded to almost illegible marks.  I plan on gently soaking them clean and giving them to my DDs because I have found the perfect, environmentally friendly, grocery bag.  It's a free pattern at:  https://www.knitty.com/ISSUEsummer08/PATTbyob.html

I knit mine out of 100% Nylon rug yarn that I got on eBay about three years ago.  My new bags can be washed, are exceptionally strong, will last forever and a day and best of all, they fit on the metal packing rack. Even the Safeway cashiers love them.