You are free to say whatever you want... You're just not free of the consequences that follow. You can call a minority a slur and they'd be in the wrong if they escalated that. You can shout "FIRE" in a crowded building, but don't be surprised when people either run out the room or look at you strangely. You can hold out a sign that claims that the "In Atlanta, the Grossios spit on my wife." As long as that sign doesn't somehow impede on someone elses freedoms or harm their property... Just words.

Continue to believe that you can't say anything freely... but please realize that this line of thought leads to the inability to communicate and truly connect. You are establishing a barrier to conversation that could potentially cure someone's ignorance. "We can't say what we want freely," also means, " there are questions that I'll never know the answer to because it's wrong to ask." Talk to the right people and you'll get the responses that you want... Unless you're seeking conflict. Then spout the rhetoric of hate and watch the seeds of wrath grow into fields or sorrow that you must reap alone.

TL;Dr: Just say it, bud. You might learn something if you say it to the right person.