We've all skipped a heartbeat at some point with this thing. Share your brown trousers stories here!
One classic moment was the first time I updated the firmware... very late at night, total silence, and it was working away and i was doing something else and POP! I almost died of fright.
My other fave was recently, when I tried testing the direct out in various modes. I put my re20 space echo pedal in the fx loop and turned up all the knobs. The amp was in standby. Everything was totally silent (again, late night with the kids in bed). I could see the effect on the direct out since I watched my signal level on my mixer stay high after hitting a chord. Then, with the master down, i turned the amp on and found out that the fx return comes in after the master, cos I got a massive blast of squealing feedback.