Worst: Arriving at Chile immigration after the bus ride from the Argentine check-post to find that my pouch with my passport, cash and everything else important was missing.
Best: Finding that the two guys I had got talking to in the queue were in fact some sort of security officials. They arranged the bus to be searched and then made a radio call to the Argentine side to get my details. During that call they found that my pouch was there - I had stupidly left it on the counter after getting my passport stamped.
These two amazing officials then arranged for me to get a temporary permit, a free ride to Santiago (with a note to tell the guesthouse I would only be able to pay later) and back the next day. We then had special permission to drive through no-mans-land and retreive my valuables. I wasn't even allowed to give the lady who kept my bag safe any kind of reward.
That would have been simply fantastic but the hospitality didn't stop there. We were given lunch and a tour of the huskie dogs before driving back to the Chilean side.
I could never thank my two benefactors enough. I did write to the Ministry of Foregn Affairs when I got back home with my sincere thanks for all involved. I just hope the special mention for these two helped their careers along.