Another quote, from here:

Most people might be surprised to realise that Auld Lang Syne is quite a long song, composed of five verses and the chorus. On New Year's Eve, most of us only sing the first verse and the chorus, probably because most of us are not in much of a state to sing any more. Most of us know the words, but just in case this is how the version most of us sing on New Years Eve goes:

"Should auld acquaintance be forgot,
and never brought to mind?
Should auld acquaintance be forgot,
For the sake of auld lang syne.

For auld lang syne, my dear,
For auld lang syne.
We'll take a cup of kindness yet,
For auld lang syne."

The original version is tinged slightly more with Scottish dialect, and I think the use of the word "sake" is a slight twist on the original, but apart from that, the song has remained pretty much intact since it was first written in 1788. Although it seems most people (including me) do not know the words, and most people, even some Scots apparently sing it incorrectly.