- Slacking off is alright, if you balance it with a healthy dose of all-nighters of work to make up for it. Meeting deadlines is all that matters, not pacing.
- Cheating and plagiarization have value, as long as there's a fair balance, and you do it properly. One person can't attend all the classes and do all the assignments, as there aren't enough hours in the day. Early lessons in crowdsourcing, before that was a word.
- Money management. Do I use my pocket change to photocopy those pages from the textbook (I couldn't afford) that I need to study, or do I use it for bus fare so I can get home and get some sleep for the first time in 72 hours?
- Learning how to learn, as others have said.
- Women will only care about how tall, rich, and physically attractive you are, for many, many years to come. Plan on being shunned for the next couple decades (in my personal case, at least)
- Bureaucratic bullshit is a fact of life. Deal with it.
I'm sure there's more, but there's my top handful.