Jim Harbaugh has always been a fan of the Michigan Wolverines, but for one night in 1999, he donned the Michigan State green and white while celebrating in the Spartan basketball locker room during their national title run.

WXTZ-TV in Detroit released the 16-year-old footage in the wake of the Michigan-Michigan State matchup this weekend, and when Harbaugh was asked why he was wearing his rival's colors, he was quick to explain.

"My sister (Joani) is married to Tom Crean, the associate head coach of the Spartans," Harbaugh told the reporter. Crean is now the head coach at Indiana.

At the time of the taping, Harbaugh was 12 years into his NFL career and playing for the San Diego Chargers.

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