Kobe Bryant got lots of snickers when he told the world that his alter ego is the black mamba, a fierce serpent known for its uncanny ability to strike at any moment with pinpoint accuracy. Now, Nike's getting on board with a new "Black Mamba " campaign, including an eight-minute online video coming in February co-starring Bruce Willis and directed by Robert Rodriguez, the man who brought the world Spy Kids. There's a social twist to the site, created by R/GA. The idea is, if enough people chatter about Kobe on Twitter (determined by an algorithm that searches for his name and other terms like speed, champion, tenacity, heart, etc.), it triggers a "Mamba Moment" that changes the appearance of the site and causes some new Kobe videos to be posted. The threshold to start is 1,500 tweets per hour, but that may increase given the amount of global chatter the agency team is seeing. Such Mamba Moments last for six hours. (If they persist, you should probably call you doctor.) Nike is sweetening the pot by offering visitors a chance to win the new Nike Zoom Kobe VI sneaker by tweeting #mambamoment. We'll see if this takes off. It's always hard for brands to create these kind of groundswells because, well, they're pretty artificial. Then again, Kobe giving himself a nickname is pretty artificial, too.