TOD:
So many of the moments already mentioned....so I will add:
Lucille Ball at the switchboard in THE FULLER BRUSH GIRL, and later getting drunk in the same movie.
Lucille Ball in EASY TO WED on finding out that her fiance Keenan Wynn wants her to marry Van Johnson to help avert a lawsuit: "What do you mean it won't be a real marriage? I say 'I do', he says 'I do', and the judge says 'You bet you do' and we're MARRIED!"
Rosalind Russell handling a typewriter, a telephone, and Cary Grant in HIS GIRL FRIDAY.
Barbra Streisand and George Segal's exchanges in THE OWL AND THE PUSSYCAT. She catches him changing his clothes:
George: Do you mind?
Barbra: Oh, you think you got something special, you think you've got something I haven't seen before?
George: One of the very few, no doubt.
For a start.