Can you get reported for refusing to play the meta?

Short answer: no

Long answer : nope

You can be reported for literally anything. A report is nothing more than a downvote: "I didn't enjoy playing with this player".

However, I've never heard of someone bothering enough people to get warned or banned just by playing unconventional champions.

People will try to get you in trouble for it--"troll!". However, it isn't punishable.

As everyone has stated, no. Anyone can report a person, and for whatever reason they want, but you need to get multiple reports on your account to even have a chance of getting banned. After an account has gotten X amount of reports, it is then sent to the Tribunal. In the Tribunal, levelheaded players will review the reports, match information, chat logs, game scores, etcetera, and determine if you really should be banned or not. In order for an account to be banned, the majority of Tribunal Reviewers must vote for that outcome. Because of all this, you will not be banned for ignoring the meta. It just doesn't happen. Now, if you decide to be an @$$H013 about it, have a negative attitude towards your team, curse, feed, or anything else like that, then you will get banned, but that's for reasons other than playing against the meta.

You can't get reported for refusing to play the meta, however not working with your team just to subvert the meta may get you reported and punished. You shouldn't feel forced to play the meta, but its also good to listen to your teammates and follow a strategy that everyone is okay with.

People can report you cause they think you might be trolling or something, but if you say "Hey, I thought up this really weird build for this champion, I'm going to try it," they can't really report you without looking like a dumbass.

A good example I know is when i was playing AP Ezreal. Really only useful for early game shutdown (Was playing mid lane) and that's what happened. I shut down the enemy, who I think was a Jayce. When teamfights started going to shit, the Vi jungle on our team started getting pissed at me for not building Blue Ez. The Singed that was top was the real problem, fed the Riven then went afk after saying "Fuck you all. Have fun Noobs." And still the Vi blamed me. Her exact all chat was "Report the Singed for afk and the Ez for being useless." She reported me after the game cause I didn't conform to her meta. I didn't exactly do bad, either, I went like 9/7 by end game. My point is, there's going to be people out there who think the meta should be in the Bible (or other Holy Scriptures) and that is the only way to play. I only have one thing to tell them; Too bad.

Yes if you're actively refusing to communicate and work with your team. If you're going jungle revive heal heimerdinger just to 'break the meta', I'm probably going to report you.

If your team wants to do something a specific way and you're blatantly ignoring what they'd like to do, then yes, I'd say it's reportable as a lack of communication.

On the other hand, if you want to do something like a kill lane bot or a dual jungle or all mid if your team agrees to it then it's absolutely fine. When I play ranked I'm fine if someone asks to do a weird metabreaking strategy, but if they completely disregard everyone asking that person not to do it it's pretty unsportsmanly and a bit dickish.

It's the tribunals decision in the end, right ?