Singing in 'rounds', first person sings once right through, then second person
Starts when first person reaches second verse, third person when second reaches
Second verse, and so on...

By the waters
The waters
Of Babylon.

We lay down and wept
And wept
For thee Zion.

We remember
Thee remember
Thee remember
Thee Zion
[ Lyrics from: http://www.lyricsfreak.com/d/don+mclean/babylon_20151546.html ]