Shit, that headline could mean anything. What it does mean is that Justin Timberlake doesn't have a sense of humour about the Janet Jackson nipple exposure affair. During a press conference backstage at the recent MTV Europe awards, a journalist attempted to present him with a fake plastic breast to commemorate that incident. Timberlake reportedly looked visibly upset and called the man a "numbskull".
To be fair, I don't think I'd have found that especially funny, but he had just been saying that he hoped that "everyone could take a joke" regarding Kanye West's invasion of the stage that night (if you remember, the rapper ran up to protest that he should have won the Best Video award, which went to Justice vs. Simian). Which all rather makes Justin seem something of a spoilsport. Which I'm sure he isn't. At all.