I'm not going to pay for my coffee this morning.
Then how do you plan to get the coffee?
I'll just walk out of the restaurant if the waiter asks me to pay.
It's completely inappropriate to walk out of a restaurant without paying for your coffee. If you order something you should pay for it because if you don't then the waiter might get into trouble.
You're just someone who likes to push rules down people's throats. I just want a free coffee.
The coffee isn't free; it's stolen. Someone still has to pay for it, whether it's just the restaurant that has to pay for the supplies you stole or the waiter who gets in trouble that he let you walk out without paying. It's wrong, and what's more, it's illegal and could get you in police trouble.