I was on a business trip to Barbados with a collegue many years ago (yes it was a rotten job, but somebody had to do it). We got chatting to a group of rather fit, bikini-clad ladies on the beach, turned out they were BA cabin crew on a stopover.
Flew home a day or two later and was served on the plane by a stewardess who looked vaguely familiar, then the penny dropped and before I could stop myself I unthinkingly came out with "Oh hello, I didn't recognise you with your clothes on!".
Fortunately the lady in question had a sense of humour.