The Vampire Diaries Season 3 Episode 15

Stefan: I lost that coin toss, Damon. It should have been me who turned Abby. Why'd you do it?
Damon: 'Cause I'm not blind. I see what's been going on around here. You're hanging by a thread, Stefan. Barely over your last ripper binge and all you want is to be the old Stefan again.
Stefan: That part of me is gone for good.
Damon: Oh yeah? How long has it been since you had a drop of human blood?
Stefan: How'd you know?
Damon: Spend a hundred and forty-six years with someone, you kind of start to pick up on their tells. Answer the question. How long's it been since your last drink?
Stefan: Since the night I threatened to drive Elena off the Wickery bridge.