The singer, who has a following of over 3 million on the social networking site, swore when tweeting a response to her rapper friend Katt Williams.
Williams posted: “Watchin clifford the big red dog =) somehow im reminded of @Rihanna idk (I don’t know) why tho (sic).”
The 22-year-old then wrote in reply: “LMAO (Laughing my arse off), Katt u lil c**t.”
A fan later commented: “Rihanna is a role model to millions of young, impressionable kids.
“She shouldn’t be using that kind of language – especially when she knows how many people follow her.”