As I said in my original post, I disagreed with the call in the Steelers/Bears game. I thought the player's behavior was within the bounds of what's acceptable.
As for defining it clearly, here's what the college rulebook says (the NFL rules are similar, but a bit looser): “Any delayed, excessive, prolonged or choreographed act by which a player (or players) attempts to focus attention upon himself (or themselves).” That's pretty much the definition of showboating or taunting. Players jumping up and down in excitement, jumping on each other, high fiving, and so on is great. Being excited and ecstatic after a big play is great. Taunting the other team, standing over a player and taunting him, grabbing your crotch, making vulgar signs to opposing fans or players, choreographed dance routines and such, etc. is something else.
In college at least, if you taunt an opponent on your way to scoring a TD, the infraction negates the score. In other words, you can't make taunting gestures or run backwards the final few yards or anything else we'd generally deem unsportsmanlike. I like these rules. I don't always like the inconsistent enforcement of them and I realize mistakes are made (guess what, they're made on PI, holding, and other infractions too), but dialing back the unsportsmanlike behavior is a good thing. We teach this to our kids in sports, to win or lose with grace an dignity... no taunting or bad sportsmanship.
