Called "Wear Your Seat", this chair may look like a backpack but actually it is a chair. You can carry it with you all the time because you have to wear it. We've heard the phrase that BYOB but as Inventor Spot notes, now it is time for BYOC (bring your own chair).
Wear Your Seat was designed by Olivier Peyricot, a French designer. The chair is basically a semi-rigid padded cushion that you can wear on your back so you can sit sown comfortably no matter where you are. Although it's not pretty, it's practical when come in a crowded room where no seat available.