As a last-minute boarder, wondering how I ask an extremely large person in the first row if the seat next to her was, uh, "taken." Ended up there was one seat in someting like Row 22, so never did have to broach the potential COS issue.

Scariest - some 30-minutes into a long-distance flight from PHX and having to turn back due to an "unusual reading" in the cockpit. Everyone was professional, but the FA's were obviously on edge. The plane was taken out of service, but they did get us a replacement in surprisingly short order.