"What's between friends?"

"What's (something) between friends?" = giữa bạn bè với nhau mà -> nghĩa là đừng bận tâm tới số tiền tầm thường này làm gì vì mình là bạn bè, thường dùng để từ chối việc bạn bè muốn trả tiền cho bạn vì nó không bao nhiêu cả.

Ví dụ 

Saudi Aramco targeted by climate action investor group -What’s a few trillion (nghìn tỷ) between friends?

Who said TVs were getting cheaper? LG just declared that it would bring its 105-inch Ultra HD set to the U.S., and named its price at one hundred large. Well, $99,999, but what's a dollar between friends? Besides being, well, huge, LG's 105UC9 LCD TV is stretched out wider than your typical screen: It has an aspect ratio (tỷ lệ) of 21:9, intended to match the widest films at the cinema. That brings its total resolution to 5120 x 2160—11 million pixels. The TV incorporates a 150-watt sound system and, yes, it's curved. 

Bài trước: "Keep it between the ditches" nghĩa là gì?