Cynthia Nixon and Christine Baranski in THE REAL THING, back in the late 80s.
Also, I'm infamous among my friends for NOT recognizing actors offstage/offscreen! During the original production of INTO THE WOODS, I sat next to Alexis Smith for the entire first act and only realized she was "somebody" when someone asked her for her autograph during intermission -- and even then I only worked it out because I suddenly recognized her husband Craig Stevens! Of course, then the knowledge that I was seeing a new Sondheim show sitting beside the original Phyllis from FOLLIES intimidated me too much to speak to her! I also had a great discussion about theater on the Metro North one night with a very pleasant woman also holding a playbill; only when it was her stop did we exchange names, and only after she said, "It was lovely talking with you, I'm Glenn" that my brain made the connection ...
(and this is a completely DIFFERENT kind of performer and fame, but then there was the time a friend of mine met me standing on line in Macy's, waiting to return something, and he found me chattering away with a guy whom he immediately recognized -- and he blurted out in too-loud a voice, "You're Joey Stefano!" Boy, did THAT make certain heads turn!)
"Sweet summer evenings, hot wine and bread /
Sharing your supper, sharing your bed /
Simple joys have a simple voice:
It says why not go ahead?"