Bill Clinton and Jack Nicklaus have it. So did Mark Twain and Paul Newman. As a whole, Green Bay Packers fans don't. It is colorblindness, and most Packers fans would rather throw out their Cheeseheads than see what they witnessed Friday night: Brett Favre in the purple uniform of the Minnesota Vikings. But Favre is not alone as a franchise icon who chose to don a rival's uniform or coach an archnemesis. Stephen Ruiz of the Orlando Sentinel looks at five others who colored one fan base red with rage when they joined the dark side. The conditions: The person must have played or coached long enough with a team to become synonymous with that team, and a player must have chosen to cross enemy lines and not been traded:
Act of betrayal: After 11 seasons with the Raiders, a reduced role and dispute with team management led him to sign with Chiefs. He played five seasons in K.C. (1993-97).
Buzz: It's hard to blame Allen for leaving after owner Al Davis referred to him as a "cancer," but couldn't he have found a home outside the AFC West?
Act of betrayal: Clemens' stint with the Red Sox (1984-96) didn't end well. After two years in Toronto, any chance for reconciliation was broken when he joined the Yankees (1999-2003, '07) and won two World Series titles.
Buzz: "Misremember"? Red Sox fans would like to forget the Rocket's playoff failures.
Act of betrayal: Began career with 16 seasons as a Brave (1987-2002) before signing with the Mets. Rejoined Braves in 2008 before being released in June.
Buzz: Glavine's 300th victory came with Mets in 2007, a tomahawk chop to the heart of any Atlanta fan.
Act of betrayal: Pitino won a national title and 219 games as Kentucky's men's basketball coach from 1989 to 1997. After a failed stint coaching the Celtics, he returned to college at Louisville in 2001.
Buzz: In light of Pitino's extramarital scandal, new UK Coach John Calipari already is urging Wildcats fans to treat Pitino with respect when the teams meet at Rupp Arena in January. Sorry, Cal.
Act of betrayal: After guiding Louisiana State to the 2003 BCS national title, he left to coach the Dolphins in 2005. After two seasons in Miami, he returned to the SEC -- as Alabama's coach.
Buzz: Saban said after his return to LSU for a game last November that his move to 'Bama was "nothing personal." Tigers fans didn't believe him.
Would they dare?
Other athletic figures we couldn't imagine joining their team's rival:
* Bobby Bowden coaching Florida.
* Kobe Bryant signing with the Celtics.
* Derek Jeter playing for the Red Sox.