The mystery of the roadside soda bottles

We first noticed them in Tierra del Fuego after we had crossed the Chile to Argentina border: discarded plastic (and sometimes glass) bottles, half filled with a liquid of a color ranging from diluted Mountain Dew yellow to apple juice brown – nicely sealed with its bottle cap. Why would people throw away half finished drinks? Maybe these were offerings to some travel saint, like the water bottles we see at the shrines of la Difunta Correa (= a lactating mother, sanctified by Argentinians after (legend says) she was found dead along a road, while her live baby was still drinking the mother’s milk…)? We could not make sense of it and decided to ask about it at the Ushuaia tourist office. She could give us no answer, so it remained a mystery, until just now our guess work was over: after we crossed the border once more from Chile to Argentina, we noticed the road side bottles again, but this time, a stopped car along the road gave us the clue: a guy alongside the car was peeing in a soda bottle! Now we can imagine the embarrassment of the tourist office lady when we asked about the bottles! It still leaves us wondering why. Why put the top back on, and why even pee in a bottle and leave it along the road, while just peeing alongside the road would have been so much cleaner…and how do they think that trash will disappear?