According to the man himself in his 2008 documentary Tyson, the tattoo represents his 'warrior status'. It's similar to the ones that members of the Māori tribe, a warrior-like tribe in New Zealand, wore to scare people in battle. Not that he needed anything more to make him scary. He also got it because he thought the design was 'cool'. He said: "I thought it was so hot. I just thought it was a cool tattoo."
After getting it done, millions have gone on to get the same. Tyson once said: "I love this tattoo. Over a million people got it now, so I did a good thing. This is good."