Here in Edinburgh, there is a large group of us who sing it far too often, genrally trying to lead a large number of people with no idea of how it goes.
We tend to sing "for the sake of", with a not too much of an accent.
This may be due to how we leant it, or us trying to make it clearer for those who don't know it, and often have shakey english. Adapting stuff to your audience is a part of the folk process.
The lang syne tends to become lang Syne,

But as I said, we're in Edinburgh, not really Scotland at all.

Bunnahabhain