"What is that?"
"Hm-"
She gets a wicked grin on her face as she slips the shard of glass between her fingers, kinda like a throwing knife, and throws it with perfect precision at a fairly drunk man in a corner, cutting his cheek as it launches itself into the wall. At that point, she quickly turns around and starts drinking her beer, looking perfectly calm and natural.
"Ey-don't look at me like that. We're just having a normal conversation, and you're just a normal bar patron. Now just watch..."
The drunk guy who's cheek she cut looks around angrily and bleary-eyed
???: "HEY! WHO THE HELL JUST DID THAT!? I SWEAR YOU'RE GONNA PAY-"
A much less drunk patron gets up and goes over to the guy
???: "hey-why don't you just take a seat and relax-"
???: "DON'T TELL ME TO RELAX!"
He drunkenly swings at the guy, trying to punch him