I forgot to bring my resume to the interview.
I FORGOT TO BRING MY RESUME TO THE INTERVIEW!!!
After the formalities, the interviewer (partner/founder of the company) asked "Did you bring a resume?"
Him: "That's fine I've seen it."
We ran out of things to talk about after 10 minutes, shortest interview of my life.
Probably not getting a second round, and this would have been the perfect opening for me.