Not propofol specific, as I'm not sure what I was administered, but "rebooted" is the best way I've found to explain it. I've only been put under once, and similarly for knee surgery.

After everything was prepped, my surgeon and I were chatting about something and the last thing I recall was the anesthesiologist putting the mask on me and saying "nemasu" (Japanese for "sleep").

There was no countdown, no drowsiness, no sleepiness -- I was just gone and then waking up post surgery. It felt as though no time had passed, but it had been hours. Completely and utterly trippy.