Cycling over Tower Bridge needs concentration, even more than on other roads. Going to work or coming home, I need to bear over to the right as I come off the bridge - so relative pace and position in the traffic lanes need to be thought out. To add a complication, there's a nasty pot-hole on the northbound lane that needs to be avoided.
So I was in no mood to be distracted by some indistinct shouting from a car to my right. It's not unheard of, whether it be someone trying to share his (it's usually his) interesting variations on motorists' vernacular for cyclists, or someone asking for directions (yes, they will do it even at some speed, and even leaning right across to the passenger-side window). But I ignored it, until I heard the word "gadget".
Then the penny dropped. He wanted to talk about my Winkku.
I couldn't make out any more, as he continued to bellow indistinctly, keeping pace alongside me, so I just made non-committal noises, until the point where he really had to decide which lane he was in, and he drew ahead to stop in the queue at the lights. I rather ostentatiously put on my indicator as I moved to the right and pulled up behind him.
He poked his head out of the driver-side window and shouted "What happens when you want to turn left?"
But the lights changed and he did not stay for an answer.