You can also get buzzers to wire into the indicator circuit to give you an annoying audible reminder. I fitted one to a bike a few years ago, and it certainly worked. I haven't bothered since.
When I went to Belgium a couple of years ago I got tired of trying to signal my three riding buddies behind me that they had left their indicators on, at times it looked like an abnormal load escort there were so many flashing amber lights It’s not bloody rocket science. Signal on, execute turn, signal off.
I have the same problem seeing the indicator on my speed twin, placing the left turn indicator light behind the tach needle, poor design! I find myself pushing to cancel the turn signal now even if is off.
BREAKING NEWS: The Taliban seen riding the dodgems will NOT be allowed immigration into the UK. A Taliban spokesman said, "This is funfair discrimination."