There are lines that no one may cross, apparently.

You can’t draw a satirical cartoon of the prophet Mohammed without risking a death threat.
You can’t say the Holocaust never happened. And, as a 20-year-old Greek soccer player learned, you can’t celebrate a goal by flashing a Nazi salute. Giorgos Katidis made the gesture – although he swears he was just pointing to a friend in the stands – and it earned him a lifetime ban from his country’s national teams.
The Hellenic Football Federation that governs Greek soccer said his action “insults all the victims of Nazi bestiality and injures the deeply pacifist and human character of the game.”
Perhaps, but it seems a harsh penalty to dish out to a possibly ignorant youth. Time World reports that when a soccer captain saluted fans with a fascist gesture during two matches in Italy in 2005, he was fined $26,000 and received a one-game ban.
Of course, soccer federations and TV network executives, newspaper editors and book publishers and the court of public opinion can all weigh in on what is allowed and what is too revolting to accept.  
But the late Christopher Hitchens had this to say about freedom of speech: “The urge to shut out bad news or unwelcome opinions will always be a very strong one, which is why the battle to reaffirm freedom of speech needs to be refought in every generation.” He defended this right even for Holocaust deniers and Nazi sympathizers who wished to publish their views. “I did this because I think a right is a right and also because if this right is denied to one faction, it will not stop there. (Laws originally passed in Europe to criminalize Holocaust denial are already being extended to suppress criticism of Islam, as a case in point.)”
We also need to teach each generation why the Nazi salute is vile.
By all means, let us teach our youth polite behavior, kindness to all, and that words can hurt. Let us laugh at or scorn those whose words and gestures are inappropriate. But do not stop their right to speak, which preempts our own ability to hear.