Rihanna has fired back at critics who have taken aim at her latest drug-related tweet, insisting she doesn't care what they think.

The R&B stunner was savaged online after posting a photo of marijuana on Twitter.com late Wednesday night (02Jan13) and writing, "This nug (nugget) look like a skull or am I just (hallucinating)....?"

Followers attacked her for setting a bad example for young fans, with one detractor stating, "Wow wat (what) a good influence you are on young girls... not," while another added, "I dont understand what she (is) tryin to prove through pics of drug everyday (sic)."

The tweets prompted the defiant We Found Love singer to post a photo of herself alongside a caption, which reads, "I Don't Really Give A F**K."