On This Day in Pittsburgh History: December 27, 1975
The Steelers wave Terrible Towels for the first time as they take the Three Rivers field for a divisional playoff against Baltimore. Andy Russell wins the game on a 93-yard return for a touchdown.  [Wikipedia] 
From Pittsburgh Magazine (2010):


In 1975, Cope’s bosses at WTAE Radio asked him to come up with a clever promotional gimmick for the station that would be embraced by Steelers fans. After considering black masks emblazoned with then-head coach Chuck Noll’s motto, “Whatever It Takes,” Cope came up with a less expensive idea: a gold rally towel.  Cope spent several weeks promoting the idea on the radio, with little apparent success. He even took a sample towel into the Steelers’ locker room for a straw poll."I think your idea stinks," said linebacker Jack Ham.  One can imagine Cope reacting to Ham’s assessment with his trademark, “Feh!” (more)

On This Day in Pittsburgh History: December 27, 1975

The Steelers wave Terrible Towels for the first time as they take the Three Rivers field for a divisional playoff against Baltimore. Andy Russell wins the game on a 93-yard return for a touchdown.  [Wikipedia

From Pittsburgh Magazine (2010):

In 1975, Cope’s bosses at WTAE Radio asked him to come up with a clever promotional gimmick for the station that would be embraced by Steelers fans. After considering black masks emblazoned with then-head coach Chuck Noll’s motto, “Whatever It Takes,” Cope came up with a less expensive idea: a gold rally towel.  Cope spent several weeks promoting the idea on the radio, with little apparent success. He even took a sample towel into the Steelers’ locker room for a straw poll.

"I think your idea stinks," said linebacker Jack Ham.  One can imagine Cope reacting to Ham’s assessment with his trademark, “Feh!” (more)

On This Day in Pittsburgh History: December 23, 1972 

In the first Steelers playoff in 25 years (and their first postseason win), Franco Harris salvages a Terry Bradshaw pass in the greatest NFL play in history—to beat the Raiders 13-7 at Three RiversArt Rooney and Bob Prince miss the play while in the elevator to the locker room. [Wikipedia; Pro Football Hall of Fame]