Had an interview for a graphic designer job in a multimedia company many years ago. It was my very first interview. I had just graduated with a degree in Fine Art, but had no industry experience. 2 days before the interview I had eaten a battered sausage that someone threw at me on the street outside Fibbers. It fell into a puddle, and I picked it up and ate it in defiance. Bad move, I was shíteing out my mouth and puking out my arse all weekend.
Anyway, I had this interview at 10 am on Monday morning, I hadn't eaten in two days, was pale as a ghost and pumping sweat from the illness, but the worst had passed on the gastro front, so I decided to go ahead. I had long, crusty dreadlocks at the time, and I think I had to borrow a suit that was too big for me, so even on a good day I would have looked an absolute state.
I had a portfolio lashed together of various art and design stuff I'd done. One thing I'd been doing in college was that I'd started my own country in my living room - so a lot of the stuff in my portfolio was to do with that (flags, posters, manifestos, etc). The two women interviewing me asked me to explain what it was all about, and I did, in probably too much detail. We ended up in an argument, with the final question being "How the hell do you expect to make money out of this?" My answer "I don't!" signaled the abrupt and early end of the interview. You may be surprised to hear that I did not get the job (only interview so far where I wasn't offered the job, so I think I learned something from it).
On the other side of the coin, I interviewed a guy a few years ago for a Web Developer job. In the middle of the interview, he somehow worked in to the conversation that he did Taekwondo, and stood up and started demonstrating some moves. Then he started telling us randomly about some tag rugby match he played, and again stood up and started re-enacting the game. Weird thing was, he wasn't even a Web Developer and couldn't answer any questions on the subject. That interview should have been cut short, but it was too entertaining.