Barbra Streisand
Almost knocked her down.
A number of years ago, I was at the San Francisco International Airport. When I exited a phone booth, I almost ran right into this very small woman with long blond hair. I said excuse me. Found out that they where filming a movie there, and Barbra was walking around the airport at the time. Saw a number of other celebrities on this same day, but this was the first...and an unexpected sighting!