Kiss and slap

Mr. A, Mr. Z , a beautiful girl and an old woman are sitting in a train. The train suddenly goes through a tunnel and it gets completely dark.

Suddenly there is a kissing sound and then a slap! The train comes out of the tunnel. The old woman, beautiful girl and Mr.A are sitting there looking perplexed.

Mr.Z is bent over holding his face, which is red from an apparent slap.

The old woman is thinking:
That Mr. Z must have tried to kiss that girl and got slapped.

Mr.Z is thinking:
"Damn it, that Mr. A must have tried to kiss the beautiful girl, she thought it was me and slapped me instead."

The beautiful girl is thinking:
"That Mr. Z must have moved to kiss me, but kissed the old lady instead and got slapped."

Mr.A is thinking:
"If this train goes through another tunnel, I could make another kissing sound and slap Mr.Z again."