what's... between friends?

What's (something) between friends?

This amount money is a trivial concern because we are friends. A: "Hey, let me pay my share for lunch." B: "It's okay, I'll get it. What's a few bucks between friends?"

what’s ... between friends?

(spoken) used for refusing an offer by a friend to pay you for something because the amount is small: ‘I owe you €2 for that coffee.’ ‘Don’t be silly, Steve, what’s €2 between friends?’