First off, the "Freedom of Speech" is not absolute. It does not give you the right to say anything you want, any time you want, any where you want. It does not protect you from the non-governmental consequences of your speech.
The right of Free Speech does not mean that you can say "Bless You" in the middle of class during school hours. It surely does not mean that you can then proceed to start an argument with your teacher in the middle of class and suffer no repercussions.
The only thing that the right to free speech affords you is that the government can not arrest you for simply saying something. Teachers can tell you not to talk in class unless called upon - including not saying "Bless You" when someone sneezes. Rules of the class. Police can open an investigation on you for saying something like "I want to kill the president" or "My heroin supplier was late, so I shot him and took all his stash." You can be arrested for shouting "Fire!" in a crowded theater or bar - if anyone hears you and a stamped occurs because you scared everyone - and fined for damages.
People are completely free to stop buying your products or shopping at your store because of anything you said that they didn't like. Your employer may fire you for saying bad things about the company.
Your right to free speech has other limits as well. You can't claim free speech when standing outside a classroom yelling the script to Monty Python and the Search for the Holy Grail. You are free to speak that somewhere else, like a public park. However, if you start doing that in a grocery store, they are totally free to kick you out.
Your right to Speak Freely is only protected from excessive suppression and obstruction by the Government. Freedom of Speech does not protect you from the social and civil consequences of what you have said.