Tybalt: Romeo, the hate I bear thee can afford

No better term than this, – thou art a villain.

Romeo: Tybalt, the reason that I have to love thee

Doth much excuse the appertaining rage

To such a greeting; villain am I none,

Therefore farewell; I see thou know'st me not.

Tybalt: Boy, this shall not excuse the injuries

That thou hast done me; therefore turn and draw.

–Romeo and Juliet,
William Shakespeare

What does the audience know that Tybalt does not know at this point in the play?

Romeo is an expert swordsman.
Romeo has set a trap for Tybalt.
Romeo is now married to Juliet.
Romeo snuck into the masked ball.

The audience knows that Romeo is now married to Juliet.