The Roundabout Way.

If you would be so kind, would you please, now, just raise your left hand in front of you. Now can you please just twitch your index finger upwards ever so slightly.
Thank you.
That was easy, wasn't it?

That's how one indicates while driving. If you can't be bothered twitching your left index finger while approaching a roundabout then, I'm afraid, I will have to come and visit you. Possibly at 4am. With a pair of pliers.
As long as your name isn't Oscar Pistorius (allegedly).