I'll heckle any opponent when I sit in the outfield. Though I do remember yelling some stuff at Wily Taveras a few years back when he was with the Reds and later in the game he tried to pull off a covert middle finger. Adam Dunn had some of the better and more funny responses back in the day when he was playing RF for us.
Shannon Stewart gets mad when you make fun of his name.
I guess he said something to an official at a game, because the fan was taken away after Shannon gave him the bird.