I almost never see teenagers taking responsibility for anything, so when it does happen, I'm extremely shocked.
When a teenager says no to me, it depends on what he/she's saying no to. If they broke something expensive and important and I'm demanding they pay for it, and they say no, I smack them. If I ask them to help me out by bringing me that hard drive that's across the room and they say no, first I bug them a little bit about it, then when they don't budge I get it myself and call them a lazy jerk.