Justin Timberlake sparked outrage on social media over the weekend after tweeting a birthday message to fellow pop-icon Madonna in which he called her his "mother chucking ninja." According to Us Weekly, people pounced on Timberlake for using the phrase and deemed it racially insensitive. The word "ninja" is widely interpreted as a stand-in for the N-word. Timberlake quickly deleted the tweet, which was meant to recognize Madonna's 56th birthday on August 16.. I didn't even know Ninja meant that.. Did you? Again I say, people are far too sensitive these days..