Um....I don't care if it's your mom, don't give other people your work unless you want an all expense paid trip to the dean's office. You never know how much your friend will change and if it will be enough to where it's not recognizable, and while you're not the one plagiarizing, you can get in some deep doo-doo for that.
As far as your roommate. If you come across that deal again, just talk it out. A majority of people will understand. If they don't, be a jerk about it...unless the dude is way bigger than you, then find somewhere (else) quiet to nap.