I never thought of asking about that song here! I've been trying to find out how that finished for YEARS - anytime I heard it at school outings etc, it was censored after the first verse. All I can remember is:

The first night I saw her she was dressed all in white
All in white, all in white,
I took her out that night
Down the back alley where nobody goes

I have a feeling the colour brown comes up next, providing a convenient rhyme for down, but I can't be sure as the teachers deemed us too innocent and fragile to hear it.