I've locked my bike to trees many times in the past...I won't be doing that any more.
Meanwhile, these guys have style. They are not prepared to steal just any bike. No, first they have to try it out. And clearly this one simply wasn't up to their exacting standards.
I can't help but feel that maybe they're a bit bored too...
For some tips on how to avoid having potential thieves test ride your bike, read here.