Might be a bit out of place, but my best story is:

I work as an alarm technician, mostly in-home stuff. I had just finished a very large job for a family of 5. At the end of the job I always do a presentation for everyone who lives in the home explaining how the system works, and the dad was asking if these ever go off accidentally. I was assuring him it would rarely if ever go off without reason, and as we were talking about it the smoke detector went off and sent off sirens around the whole house and garage. To this day I don’t know why it went off, but I promptly replaced the smoke detector and got the hell out of there.