Tybalt is a hot-headed, vain jerk who hates the Montague's with every fiber of his being. He is the cousin to Juliet, and when he sees a Montague by the name of Romeo at the party, he immediately rushes off to tell Capulet.
Capulet Stops Tybalt
Calm down and leave him alone.
Tybalt confronts Capulet about Romeo, approaching him from behind to talk. Capulet holds a wine glass, and is enjoying himself and absentmindedly spinning it in his hands. Tybalt begins to go on a rant, getting angrier and angrier through his expressions and words.
Capulet stays firm
But we're being disrespected!
You will tolerate him!
Tybalt goes on a tirade, pacing back and forth in front of Capulet before he points at Romeo to make a point of the Montague.
Tybalt exits
I'll leave for now, but I'll get you Romeo!
Lord Capulet, clearly not amused, tells Tybalt to stop his shenanigans.
I won't tolerate him!
Tybalt argues with, getting angry with Lord Capulet. Capulet eventually throws his glass on the floor and yells at Tybalt to leave.
You insolent boy! Get out of my sight!
Tybalt exits in a huff as Romeo walks towards Juliet, love-struck, and completely unaware of what just happened.