It used to be they could basically pin that to the top of a persons News Feed. They removed that ad unit, now, when you pay for an ad, you just get the social context of who likes that product. Since you are using Facebook, a platform with an explicit goal of connecting the world through sharing, it shouldn't be surprising that what you do on it will be seen by others. This social context will only show to your friends, by the way, since people who don't know me are probably not that interested in the fact that I like Topo Chico.