mine was very similar to matt_mcg's. It was at a university boxing club sparring session with head guards. I was trying to practice good blocking form and footwork with medium counter punches and jabs, but the guy I was up against was clearly out to prove something and was trying to knock me out. He kept smothering me and hitting me with all he had (with little to no form or composure) and I was getting quite battered and bruised, but the hits weren't really bothering me at first. Eventually, though, he punched me hard twice in the nose quite intentionally (since he was trying to hit me anywhere there wasn't the headguard), and I lost my temper and form and pretty much street brawled him into the corner. The coach stopped it pretty quickly. The rest of my times sparring I avoided the kid and boxed against guys I knew were professional and were actually trying to learn something.