Actually, I was the interviewer.
Although the main interview and hiring is done by someone else, they are sent to me for 10-15 minutes at the end since I'm the person they will directly be interfacing with.
I always get a print out of their resume beforehand which I glance at during the interview..
Well today I had an interview and it went fine. At the end we got up and I told the woman that it was nice to meet her and we'd let her know.
But, since the resume has absolutely no future use to me, I was absentmindedly ripping it up and throwing it in the trash in front of her as I said this. The look of horror on her face was tangible.
It was only about 15 seconds after she walked out the door that I realized what I had done and how soul-crushing it must have felt!
So to poor interview woman I say now: "Sorry! You were actually a decent candidate!"
EDIT: Update: https://www.reddit.com/r/tifu/comments/3f21g0/tifu_on_a_job_interview_that_went_well_until_the/