How badly can it hurt to get 2 adult teeth pulled?

Talk to the dentist: Try not to worry to much about the extractions. With proper anesthetics, novacaine, you will not feel anything during the extraction. If you are very worried then talk to you dentist or oral surgeon about being sedated. Many patient find sedation makes the procedure much easier for them. So talk to the dentist about what will be best for your individual case.

Depends: Perception and response to pain is an individual characteristic. Your mouth will be or should be numb with local anesthesia, but you can still feel pressure and hear some noise. If you do not want to feel anything or hear anything, you may want to consider being sedated.