It's not fairly uncommon for coaches to steal other teams' signals and give their team an advantage in that regard. However, most of them won't admit to ever actually doing it. That is, unless you're Tommy Bowden and are no longer looking for a coaching job.
Bowden was on "The Pulse" podcast and was discussing the Wake Forest-Louisville plan stealing controversy when he might have unleashed one of his own. He admitted to stealing signals and trying to find any shred of gameplan the Gamecocks left behind before the big rivalry game each year.
He said after a team's Friday walk through the graduate assistants on staff would go look through the locker room and trash cans to see what players had left behind. Bowden himself said he would sometimes leave behind fake play sheets to mess with other staffs.
That might explain how he beat South Carolina eight of the ten times they played each other during his tenure. "I remember Charlie Strong at South Carolina, we got when he blitzed and it helps with your call," Bowden said. Strong was at South Carolina from 1999 to 2002 and Clemson won three of those contests.
[h/t Saturday Down South]