Assbanter is the bantering with someone you consider to be an ass at the time. It's a form of dialog that may be considered passive aggressive, or argumentative in nature.
It can be an exchange of light, playful, teasing remarks; or may be be good-natured raillery. It may also be a tolerant form of dialog where each person strives to be the bigger ass.
A hardo is a person who tries extremely hard at everything. Most times a hardo will try very hard at things that do not require excessive effort. For example, sports practices, gym class, etc.
Wow did you see Jack at practice today? What a hardo!