Is it time to start calling out bad cyclists?

I go by; arm high is turning, arm low is changing lanes, and opposite arm around the back is just a little movement within the lane.

WTF? Do people actually do this? That's confusing as hell, no wonder car drivers get frustrated. What's the difference between 'arm low' and just pointing out a pot hole?

Here comes an obstacle, I'll take one hand off the bars and put it behind my back. Well that's really fucking sensible.

Not ranting at you Tenners, just the concept.