I treat my possessions well.  I'm known for it.  I wash and vacuum my car.  I don't drop or scratch my cell phone or camera.  My computer screen doesn't have any finger smudges. 

I'm usually berated for this.  Well actually, I'm berated for forcing other people to follow my rules.  I fail to see this as a problem.  If you use my computer, I don't want your grubby fingers on my monitor.  If you're in my car, I don't want your food and garbage all over the place.  I unfortunately spend a lot of money to have nice things, and my goal is to keep my things looking and working well as long as possible.  I bought my car in 2004 and it looks and drives 90% as good as it did when I first got it.  My friend bought his car a few months later and it looks like he just drove it through a dust storm with the windows down.  I know a person who's dropped her Blackberry on the ground so many times, the thing has actually changed shape.  I, on the other hand, kept my phone is such good condition that I was able to sell it on eBay after two years of regular use. 

My point is this:  When you use or borrow my stuff, treat it like it's my stuff, not your stuff.  You may be accustomed to dropped your things and breaking your USB ports, but I'm not.  If you don't like my rules, get your own stuff. #psychology