The UK rules for signalling and interpretation of other vehicle's signals:
(please feel free to add more)
Flashing orange lights on the left hand side of the vehicle: I've accidentally knocked this lever by the steering wheel. Does it matter?
Flashing orange lights on the right hand side of the vehicle: I've accidentally knocked this lever by the steering wheel. Does it matter?
No orange lights flashing: I'm either about to turn left or turn right but may go straight on instead.
Any orange lights flashing: I'm either about to turn left or turn right but may go straight on instead.
Cyclist with either arm in the air: I'm going to manoeuvre so please overtake me and immediately turn left.
Cyclist with right arm in the air: I'm going to turn right so try to overtake me before I do.
Cyclist with left arm in the air: I'm gong to turn left so pulling out in front of me from your side turning won't work
Flashing orange lights on all corners of a stationary vehicle: I'm parked illegally.
Flashing orange lights on all corners of a moving vehicle: I'm doing something stupid but as I own the road get out of my way.
Green light on a pole: Keep going
Red light on a pole: Keep going