Twitter (NYSE: TWTR) recently introduced Promoted Stickers, which are company-branded stickers users can post on their photos. It might seem like a long shot to expect users to turn their own photos into corporate ads, but Pepsico (NYSE: PEP) is already offering almost 50 stickers for the platform. Will this effort help Twitter squeeze more revenue from its users as its user growth stagnates, or is it destined to flop?