The teams have played all but six years since their first meeting in 1915. They did not face each other in 1919, 1920, 1925, 1987, 1988, or 2006. Although no longer in the same conference, SMU and TCU agreed to play each season through 2017 on an alternating home-and-away basis.
Two different versions of the story. In recent years SMU's website has claimed the following. TCU and SMU fans began the tradition back in 1946. During pre-game festivities, an SMU fan was frying frog legs as a joke before the game. A TCU fan, seeing this desecration of the "frog", went over and told him that eating the frog legs was going well beyond the rivalry and that they should let the game decide who would get the skillet and the frog legs. SMU won the game, and the skillet and frog legs went to SMU. The tradition eventually spilled over into the actual game and the Iron Skillet is now passed to the winner.
An article from TCU magazine tells the following story. "The first "Battle for the Iron Skillet" occurred on November 30, 1946, as college football boomed after World War II. Weeks prior to the game, SMU’s Student Council proposed the idea of presenting a trophy to the winning team. TCU accepted the idea, and the two schools' governing bodies met in Dallas to set up the rules of the traveling trophy, which became the Iron Skillet."  The TCU magazine article has this to say about the other story "One mystery remains: Why a skillet? History books provide scant details. Some claim that an SMU fan in the 1950s was caught frying frogs legs in a skillet at a tailgate before the game, and a TCU fan wagered that the winner should take the pan home, but that conflicts with a published report of the skillet originating with the councils."