For many adult Americans, the ad breaks during this year's Super Bowl may have been the first time they had heard of online marketplace Temu and its call for consumers to “shop like a billionaire.” But for millions of teens, Temu has already been a buzzword for some time. Since its launch in the U.S. last September, the Boston-based sister company to Chinese retail platform Pinduoduo has rocketed in popularity, becoming the second-most downloaded marketplace app in the U.S. last year, lag