Generally speaking, crossing from one country to another is a time consuming process filled with lines, visas, passports and stamps. In my experience, few places can compete for the ‘patience is a virtue’ award than border crossings in South America. A friend of mine recently waited 10 hours to cross into Bolivia for no other ostensible reason than the whim of the officer on duty.
If you’re going to have to wait though, the least you can hope for is some kind of distraction. This may come in the form of a new friend, some great photo opportunities or a cultural experience. Or it may come in the form of a crazy-looking feral Patagonian sheep that decides it has a beef to pick with your friend.