A person who ruins a party by either stopping the fun or not participating in a certain activity.
Jeff is a party pooper because he won't play Spin The Bottle.
'Quality Banter'. This type of banter is normally provided by people with the highest of intellect and knowledge on all things banterous. Some would say that the type of people to engage in Quanter are typically too cool for school or LADS, mostly called Caz or Rich.
I had some hardcore quanter with the pope the other day.