Jonathan Wolff (UCL) has an amusing column on the topic here, which starts with the following great anecdote:
Several philosophers claim to have had the following conversation on long-haul flights: "And what line of work are you in?" "Me? I'm a philosopher." "Oh, really? And what are some of your sayings?"
UPDATE: A reader writes with another amusing anecdote:
My husband is very proud of my daughter's philosophy education. When she was doing her master's degree a passenger on a plane asked us during chit-chat what our children were up to. My husband said (a bit pompously, I thought) about our daughter, "She is a philosopher."
Our co-passenger answered without batting an eyelid ( she was kind enough to withhold the eyeroll): "Aren't we all?"