Actually, I just remembered this morning that I've had 3... the most recent one was about 3 years ago at the dentist.
I have a morbid fear of dentists and had to go in for an extraction. They recommended an oral sedative for the anxiety. Took it... waited the recommended duration... still felt pretty panicky. Went ahead with it anyway.
Dentist gets in there, does his thing and they start to sit me back up when I felt that pre-seizure feeling. Had enough time to warn them (which was nice of me, I thought) and then next thing I know I'm looking up at the ceiling and wondering why everyone's looking down at me, and hey, my wife's here... wait, she was in the waiting room, why is she here? And then the "disk restore" kicks in and I realised that I'd rebooted. Apologised to the dentist for biting him (don't remember doing it, but apparently I'd bitten him as he was attempting to put something in my mouth to prevent me from gagging).
The funniest (at least to me) bit was in the waiting room as they're wheeling my groggy ass out. Sometimes after I seize, the nausea hits me and I lose my lunch. I can time it to within a second usually. This time, sure enough, here it comes. I tell my wife "Hon, I'm sorry but I'm gonna puke in 6 seconds."
Mass panic ensues as the twit of a receptionist tries to find something "suitable" for me to barf in. My wife keeps her cool, says "Just gimme the damn trashcan, ok?" and right as I hit 1, yay, trashcan in front of my face, thank you dear.
Went home, took a warm bath, went to bed n slept for 18 hours.
edit: we did finally discover that one of my main triggers (aside from panic/anxiety) was pseudoephedrine hydrochloride.