Ignore that person.
Try to talk to that person and see how that person's day has been going.
Ask that person to sit with you one time, that way you don't feel guilty.
Give them the pizza.
Try and talk it out.
Laugh and eat the pizza in front of them.
Insult them back
Turn the other cheek.
Laugh it off and ignore it.
Smile and go along with the insult.
Turn it up louder.
Make up a complaint about your neighbor and call the police.
Slap some headphones on. No big deal.
Apologize to your neighbor and turn it down.
Hold the door.
Slam the door.
Tell the person to hurry.
Hold the door while thinking bad thoughts about that person.