Because you get it wrong every year.
You've heard this song loads
It even turns up at the end of movies.
But it's sung most often when the bells strike midnight on New Year's Eve
Or Hogmanay, as Scottish people who are actually professionals at this stuff, call it.
It was mostly written by Robert Burns, Scotland's national poet
He's thought to have based the first verse and chorus on a traditional song, before doing the rest himself.
Auld Lang Syne roughly translates from Scots into English as "days long gone"
So it's a song of nostalgia.