I don't really think something like that needs a reason; some people are literally just like that.
Of course, somebody else might disagree with me on that. I dunno.
"Jack, you have debauched my sloth."
Just saiyan, but an entire plot based on a for the lulz protagonist sounds really boring.
Decemberist
This could be either really funny or really bloody stupid.
I think it would be better as a black comedy than, say, slap-stick, but...
As for justification, you have it in the thread title. He's a villain protagonist who fucks with people because why the fuck not?
"Shit, our candidate is a psychopath. Better replace him with Newt Gingrich."
Um, I think there's a bit of a misunderstanding. I don't need a justfication, I've got that sorted. I'm asking for suggestions of things that someone like this would get up to.
As for the character himself, here's a couple of quotes that give an idea of how his mind works:
That makes him sound like a D&D adventurer, TBH.
Never played D&D. I sort of get what you mean though. It should probably be noted that the story is written in diary format.
The possibilities are literally endless. All you have to do is put him in a situation, and think of an opportunity to troll someone in it.
I've got a character who's Walking the Earth and who has a) a very low boredom threshold, b) a tendency to do things solely because he felt like it, and c) a habit of messing with people (to put this in perspective, he once convinced a guy that he was a Humanoid Abomination and told him that he'd help him in exchange for a 'favour'). While I've got the main plot sorted out, I still need to come up with incidents to help establish that this is a very strange individual with an equally strange idea of what's amusing. Unfortunately I'm currently drawing a blank so I thought I'd ask for help.