Who’s counting?
Definition 1 of 1
Pro Tip 1/3Sarcasm Indicator
The phrase often implies sarcasm or a humorous tone when highlighting unnecessary counting or details. 
You're five minutes late... but who's counting?
Pro Tip 2/3Minimizing Importance
It's used to downplay the significance of a number or to suggest it shouldn't be a focus of concern. 
He's watched this movie four times now, but who's counting?
Pro Tip 3/3Informal Usage
The phrase is casual and best used in informal conversations, often among friends. 
Sure, I've lost to you in chess ten times, but who's counting?