Every situation is different. Can you elaborate a bit more on what happened?
I can usually verbally shred someone to the point where they will walk away with their tail between their legs. I've even had their own friend's laughing at them.
OTOH, if someone throws a punch at you, you have a right to defend yourself to a point, meaning that once the threat has been neutralized you can't kick the crap out of someone once they are down or they are backing away from you.
Check your local and state laws as well as they can and do differ.
98/100 times, if someone wants to fight you, they're not going to talk about it, they're going to do it.
And as mentioned above, it's not worth going to jail over some drunken idiot who grabbed your g/f's ass.
Call the cops on 'em and let him spend the weekend in jail, not you
Or end up getting get kicked out of school.
Let him mess up his future earnings potential with an arrest record, not you.
Over what? Some Friday night, drunken machismo?
Unless someone else throws the first punch, it's all going to be a bunch of yelling back and forth and no one will throw a punch until there are plenty of people in between.
If someone gets in your face for no reason, tell him to grow up, get laid, and chill out.