For old times’ sake
Definition 1 of 1
Pro Tip 1/3Nostalgic Motive
The phrase is used to express an action motivated by the desire to relive fond memories. 
Let's visit our old school for old times' sake.
Pro Tip 2/3Emotional Bond
It signifies a shared history and an emotional connection with people from the past. 
They gathered for a reunion for old times' sake.
Pro Tip 3/3Informal Usage
It's a casual expression, suitable for personal conversations rather than formal writing. 
We'll have a drink together for old times' sake.