Besides shopping, eating, sightseeing, etc, what other interesting things you have discovered on your trips?
Some friends do cars-spotting, it can be spotting exotic, supercars, or rare models.
Or pick another tourist and guess his or her nationality before you hear he speaks.
Sometimes when wife or gf is busy shopping, we men have to kill time while waiting outside the shops
I tried pickpockets-spotting in busy train stations, market places in Europe where the cities are notorious for these pickpockets.
So far have spotted a few suspects, but no luck seeing them in actual actions. Maybe they are so good, my eyes were too slow to catch their actions!!?