The MTR is well-known for bombarding passengers with an endless stream of PA announcements.
But the tactic doesn't work; Hong Kongers have learned to tune it out, just as they do with ringing mobile phones, traffic din, jackhammers, loud conversations, and the organised chaos that is dim sum.
It's the only way to stay sane.
Case in point: I had just alighted from the train and was walking along the station platform toward the exit when the following message was broadcast:
Please wrap your spit before disposing it in the litter bin. Spitting onto the floor or into the litter bin will be prosecuted. Thank you for your cooperation.
At the precise moment the announcement finished, a man passing between me and a garbage bin hawked a loogie, leaned over, spat it into the container and continued on his merry way.
Because he knew that in order to be prosecuted someone first has to catch him in the act and care enough to write out a summons. In other words, it's an empty threat, ergo he could safely ignore it. Which is pretty much what everyone else does.
Nevertheless, the MTR continues with this strategy in the hope of educating the unwashed masses (this particular message is played far more often in New Territories stations than those on the Hong Kong side, indicating the problem is more pervasive in the hinterland). I know of no other city where people are asked to "wrap your spit", other than Beijing, which only adopted the idea to clean up its image for the Olympics. Good luck with that; if the plan hasn't worked in Hong Kong over the past few years then breaking mainlanders of this habit in just a few months will be impossible.
So why haven't I tuned out the announcements? Because there's a certain perverse entertainment value in watching folks behaving badly.