They have been doing this for a month or two at Fisherman's village here on Samui.
People trying to head home only to find that their bike has been chained to all of the others, or that there is a clamp on the car.
There is a note taped to the bike/car explaining where the police are and to go and pay the fine.
It has become a big money earner for the police.
On my last visit there, there were about 30 or more bikes chained up and 20 or so cars with clamps.
Not bad for one night.
One twit was even trying to drive home with the clamp still attached to the car.
It did not end well.