The fame of the phrase "don't muff it" in a BYU context stems from the November 2000 renaming of Cougar Stadium by President Hinckley on behalf of the BYU Board of Trustees, which he chaired at the time.
Minutes before the renaming at center field, President Hinckley said the following to the football team gathered in the locker room:
"This is your last chance to get a victory for LaVell on his home field.
"Don't muff it.
"We'll be right behind you - boosting you, pushing you - doing everything we can to make you win this game and then just one more victory next week."
On that Saturday night and on the following Saturday in my hometown of Salt Lake City - and to the disappointment of all who want BYU to fail - the Cougars followed the prophet and... didn't muff it.