Some other circumstances that might dictate what your response is could include (but not be limited to):
Are there witnesses? Would they perceive your actions as "taking it to the next level" when the other guy was "just messing around"?
Where are you? If you're still in high school and you visibly slap someone, even lightly, you're getting punished for fighting because of most schools' draconian penalties for kids who defend themselves.
If you proceed to strike someone or choke them out in front of a bunch of people, you might be getting contacted by a personal injury attorney that isn't interested in how it started, but in how his "client's life has been forever and irrevocably changed by your excessive force" or some such crap.
Sueing someone to get rich is practically the new American Dream. Watch yourselves! Witnesses aren't always neutral!
