Adjective used to describe all things Rihanna. May also, but not always be used to describe someone or something that is equally stupendous. May never be used to describe anything Beyonce.
Mallory: Did you hear Rihanna's new song, We Found Love?
Marjory: Definitely, isn't it great?
Mallory: No it's Rihannatastic
Marjory: Definitely, isn't it great?
Mallory: No it's Rihannatastic
by Mrs.O'brien November 18, 2011
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