fine feathers make fine birds

birds and bees

Informal education about sex.

birds of a feather

People having similar characters, backgrounds, interests, or beliefs.

birds of a feather flock together

People of similar character, background or taste tend to congregate or associate with one another; it is easier to establish friendships with people that one has a lot in common with.

cannot make it

Cannot reach satisfactory or expected standards or do something competently; describes someone in a hopeless situation.

chance'd be a fine thing

Synonym of no chance or fat chance, with a somewhat more cheerful attitude.

charm the birds from the trees

To behave in a very charming manner.

doctors make the worst patients

It is difficult to advise people on subjects that they are experts on.

down to a fine art

To a point of exceptional proficiency.