We do say good boy- good girl if it's a bitch, but we never say woman's best friend, cause that could mean totally different thing. Women don't have best friends... they have a girl friend or gay friend they talk trash about behind their back.... or woman's best friend is ....glass of wine, tampons, dildo, eye liner....
the second bests
The only reason it's called man's best friend is because huMAN not huWOMAN