As far as I know, the only idiom with πρέφα is παίρνω πρέφα, including its negative δεν παίρνει πρέφα, which used to have a more general meaning i.e. he is clueless.
There is also the proverb η πρέφα θέλει υπομονή και το πικέτο τέχνη (second part of it can also have an obscene alternative: και...