A bus is pulled into a bus stop. You are a reasonably nippy cyclist approaching from behind. You have clocked that people have finished getting on and off, and seen the left indicator stop blinking. You could put the hammers down and get past the bus without holding it up for more than a second, but that might lead the cars behind you to follow, in which case you will have been at the vanguard of an antisocial manoeuvre. In other words, you are the person who should be letting the bus out. If you were in a car, you would flash your lights, and that would be sufficiently intelligible to the driver that she would barely need to hesitate in the mirror-signal-manoeuvre routine. However, in the absence of such an unambiguous signal she will see you in the mirror and, not wishing to kill you, will hesitate to pull out. How do you make it clear for her that it's alright to do so, and avoid the silly courtesy stand-off where no-one wants to go first? Try not to mention Hitler or to divert the thread into an obsession with opening doors...