L and the Milk

This is the story of L and the Milk. L is a German boy traveling in Canada over the winter. L has a degree in Geography and has never lived with anyone other than his family.
This winter, he decided to rent a room that he found on Craigslist. His roommate was uncommonly gorgeous and intelligent and he had a difficult time looking her in the eye, or coming out of room to spend time in the common areas of the house.
His roommate had just started drinking milk again regularly, after a summer of full swing dairy in which she realized that it wasn't worth drinking the milk of America's most water-consuming crop, especially since it makes everything taste worse (Still better than soy maybe). She had broke down one particularly cold week and bought a two liter carton, since she foresaw the need in the coming week for many hot chocolates.
L, as was customary, had bought his own large carton of milk. However, he was so shy he had trouble asking where the recycling was kept in the house. Once he finished the milk he left the empty carton in the fridge, and simply placed a new one next to it.
One day, his roommate opened the fridge to find her own half full milk carton, accompanied by his empty carton (which she removed and recycled for him), another half full carton and- what's this?- an entire full four liter jug of milk.
This is unfortunately where the story gets more difficult to tell as the author cannot fathom what a person could be planning to do with that much milk, especially since it goes bad so quickly. This is not the sort of product that one buys in bulk to save for a day when there is nothing else to eat.
The roommate, though deeply confused, did not have the chance to ask L what his intentions with the milk were as he had a tendency to stay out late and sleep in late.
The roommate went to visit her parents for two weeks over the Christmas holidays, and in this time forgot completely about the milk. When she returned to resume her studies in the new year, however, she found that the nearly full four liter jug of milk was still in the fridge, with a thick layer of scum rimming the top.
When L left the house to continue his travels, he took the milk with him.