Ringmaster: Vince McMahon and the Unmaking of America by Andrew Riesman:
For years, the Undertaker had worn a black trench coat during his walks to the ring. That article of clothing abruptly became a problem on April 20, 1999, when two high school students who had sometimes identified themselves as the “Trench Coat Mafia” walked into Columbine High School and murdered twelve students and a teacher.
The news media started to cast blame on violent pop culture. USA Today ran a story in which they juxtaposed Taker’s trench coat with those of the killers. As a result, Taker didn’t wear the coat at April 25’s Backlash ’99 PPV. He did, howver, kidnap Stephanie once again at the very end of the show.