College is mostly only composed of three elements. There are classes, those pesky things between waves of social contact and sleep. Students should spend around 90% of their time focusing on classes. In reality, however, most students spend about 20% of their time actually studying. It probably increases throughout a student's college career, but since I am only a freshman, I can only account for so much.
The other element of college life is the social aspect. Purely platonic relationships take up about 30% of a college student's life. They can be friends, roommates, suitemates, and friends of friends with whom you are forced to see on a regular basis.
The last 50%, at least for the men in college, is spent on trying to have sex. It is why we do things and it makes most of our decisions for us. The libido controls way too many aspects of our life. It makes sense, though, because the only way a species can survive is if they live long enough to be able to reproduce. The human race is just fulfilling their part.