Despite having the word 'banter' in its name, someone described as a Bantersauross have no banter whatsoever. In fact, they are usually the brunt of the jokes.
Someone who thinks of themselves as really cool, and can be used to describe someone who is boasting about their friends/weekend/awesome party. Usually used in a sarcastic form.
"So there were like 3000 people at my party last night and they all love me..."
"Oh, you bantersaurous, you!"