If you are learning a language of an Eastern European country, and you're offended by these childish sentences, you will not be able to cope with those cultures. They have not been hypersensitized like Americans and Western Europeans.
Learning a language in a bubble does not prepare you for using it in a real world context, and the majority of the languages on Duolingo are spoken in countries with significantly different cultures than what US/UK English speakers are used to. In Romania, they still call you fat, call people retarded, they will openly argue politics with you, and it is exceedingly common to talk badly about gypsies. They aren't actually rude, but they have not been indoctrinated with the idea that you have to censor yourself based on what might make someone uncomfortable.