"What role do you play?"
It's basically the "What's your major?" of League of Legends. Meet a new friend who wants to hit the rift with you? You ask what role they play. Meet a cute girl (or boy!) who's obviously into League? You ask what role they play. It's the safe, noncommittal question that gets the conversation started.
It's also a question that perpetuates one of the most destructive lies in League of Legends. The moment you enter into any queue in League, you're committing to playing one of three roles: your primary role, your secondary role, and support. If you define yourself only by what your primary role is, you'll lose nearly half of the games you play where you end up on another role.
When friends ask me what role I play, I instead answer with the roles I don't. My top lane pool is limited to just Maokai, so I consider it my worst role, and my mechanics are too weak to consider myself a good ADC. That makes me a mid laner, a jungler, and a support player, not a mid laner, despite my playing more games in mid than any other role. In fact, the only champion with whom I have Rank 7 mastery is a mid laner, yet I still don't define myself that way.
Ranked queue is a social contract. By entering into it, you're committing to give your all to make your team win. I don't go into ranked with my primary role set to top lane -- that would accomplish exactly the opposite. Thus, why would you enter into solo queue knowing full well that your secondary role is much weaker than your primary one? Why would you enter at all if you plan to just helplessly shrug and call the game a loss if you get autofilled to support, and you will get autofilled to support eventually.
If you primarily play ranked with a group of friends and can be assured the same role every game, then you can completely ignore this advice. The majority of us don't have that luxury, however, and have to slog it out in solo queue more often than not. To all my fellow solo queue warriors, I issue this challenge: make your secondary role as strong as your primary. Doing any less makes you a liability to your team as often as not, and if you truly don't have the skill to manage playing multiple roles on a similar level you don't have the skills built up to compete in ranked play. Remember, ranked isn't where you learn and practice, ranked is where you prove your worth and measure yourself against your closest competitors.
The only way you can ever know what your true rank is by giving it your maximum effort. That's impossible if your secondary role and support are so weak that you lose those games. Learn support. Learn your secondary. If nothing else, it will make you a better player since you'll learn what people who play those roles look out for. My ability to avoid ganks in the mid lane and judge when the enemy jungler is likely to be around my lane is based entirely upon my time playing jungle. You'd be surprised what learning another lane can teach you about the lane you main. A well-rounded player is the best sort of player. Ascribe to be that, and earning LP will be a mere trifle.