for auld lang syne/for old times' sake

for old times' sake

In honor of old memories. I'm going to be late tonight because I'm meeting up with some of my old co-workers—we're getting a drink for old times' sake.
See also: old, sake

for ˈold times’ sake

because of pleasant memories of things you did together in the past: I saw John Smith today. I hadn’t seen him for years. We had a drink together for old times’ sake.I lent him the money for old times’ sake.
See also: old, sake

for auld lang syne/for old times' sake

In memory of the good old days; for nostalgic reasons. This expression today is invariably associated with the song Robert Burns allegedly took down from an old man’s singing in 1788. Presumably it began its life with an emphasis on remembering “auld acquaintance”—that is, old friends—which appeared about 1670 in a ballad by Francis Semphill and repeated a phrase that was already proverbial. The anglicized version, for old times’ sake, probably dates from the same period. Eric Partridge deemed both to be clichés by the mid-nineteenth century.
See also: auld, lang, old, sake, syne