For context, go back about nine years.

[otherbill]

Should auld acquaintance be forgot,
and never brought to mind?
Should auld acquaintance be forgot,
and auld lang syne?Chorus:

For auld lang syne, my jo,
for auld lang syne,
we’ll tak a cup o’ kindness yet,
for auld lang syne.
And surely I’ll be your pint-stowp!
and surely ye’ll be mine!
And we’ll tak a cup o’ kindness yet,
for auld lang syne.(Chorus)
We twa hae run about the braes,
and pu’d the gowans fine;
But we’ve wander’d mony a weary fit,
sin auld lang syne.(Chorus)
We twa hae paidl’d i' the burn,
frae morning sun till dine;
But seas between us braid hae roar’d
sin auld lang syne.(Chorus)
And there’s a hand, my trusty fiere!
and gie's a hand o’ thine!
And we’ll tak a right gude-willy waught,
for auld lang syne.(Chorus)

Harry: What does this song mean? My whole life, I don't know what this song means. I mean, 'Should old acquaintance be forgot'? Does that mean that we should forget old acquaintances, or does it mean if we happened to forget them, we should remember them, which is not possible because we already forgot?

Sally: Well, maybe it just means that we should remember that we forgot them or something. Anyway, it's about old friends.