There is an episode of 'South Park' where the kids get a pretty new substitute teacher. All the boys have a crush on her, and want to be her boyfriend.
Chef tells them they're wasting their time, because the new substitute is a lesbian. The boys aren't quite sure what he means, so Chef explains that lesbians are only attracted to other lesbians.
Later the boys go over to Cartman's house, only to find him licking the carpet. When they ask what he is doing, he says that he asked his mom about lesbians, and she told him that to be a lesbian you have to lick a lot of carpet.