Ways not to lock your bike

When something like that happen, I usually make a point by moving the bike somewhere completely different but viewable to the owner so he can find it.

hopefully it's enough to make the owner realised that the bike will go walkie if he keep this up.

So you pick up someone else's bike and walk away with it (albeit not very far)?

I wouldn't look forward to the day the owner is around to see you walking off with their bike, and you have to explain to them that you were just "teaching them a lesson."