I let a friend ride my pristine condition Honda Reflex when we were 15. He started hauling ass around like it was a motocross bike, target fixated on a large rock pile, grabbed a whole bunch of front brake and no rear and promptly endo'ed it directly into thus said pile of jagged lava rocks. Forks were bent, bars were bent, instrument cluster was shattered, the fuel tank had a huge dent in it, and the fender was broken
He was a little scraped up too, but ok.
It wouldn't have bothered me much except I had only had the bike a couple weeks, and he never even offered to pay to repair it, in fact he refused, said there was something wrong with the brakes
What, like they actually worked?
Anyway, the list of people who I'll let barrow my bike now is one name long. We have an agreement if he wants to take a n00b dual sporting, HE can ride MY bike, and the n00b can ride HIS. It works the same way if I want to use one of his bikes to take a guest riding.
He has more bikes then me, and he says I can ride anyone of them anytime I want, but I use this privilege vary sparingly, not wanting to be the jerk that totals a bike that's not mine.