Any friend of

Any friend of someone('s) (is a friend of mine).

Cliché. I am always pleased to meet a friend of someone I know. (A pleasant response when meeting or being introduced to a friend of a friend.) Fred: Well, nice to meet you, Tom. Any friend of my brother is a friend of mine. Tom: Thanks, Fred. Nice to meet you too. John: Thank you so much for helping me find Sue's address. Sally: You're welcome. Any friend of Sue's.
See also: any, friend, of