Someone who is an absolute douchebag twat; Someone who has no real comprehension of others and the world, acts selfishly and arrogantly, and generally acts in a way to better themselves whilst aggravating those around them; Someone who has no understanding and comprehension of others' lives and desires, and acts in a shallow and demeaning way with apparent ignorance and stupidity.
"I just got a reply to my online forum post. This guy must be an absolute tosspot. Look what he's written!"
Can be defined as an act of folly by an individual or group; exuding a negative yet humorous quality such as: self-indulgence, delusions of grandeur, blind stupidity, beaurocracy, incompetence etc.