I never, ever copy paste code, unless it's really long. I always end up rewriting everything myself, so I have the time to think about what's happening.
Hmmmm. I'm the other way round. I copy and paste short snippets because I'm lazy and I can see if they are ok at a glance. Longer code I'll go through line by line and try and 'touch' each line to force me to think about it.