egy húron pendülnek

egy (“one”) húr (“string”) -on (“on”) pendül (“sound”) -nek (“they”), literally: "they sound on one string".

• IPA^(key): [ˈɛchuːronˌpɛndylnɛk]

egy húron pendülnek

1. (idiomatic, colloquial) they are birds of a feather, they are tarred with the same brush (they are alike)
   • 1884, Mór Jókai, A lőcsei fehér asszony (The White Woman from Lőcse), chapter XL:

     Éppen most volt szerencsém megérteni, hogy a nagyurak ígérete meg a beteg ember fogadása egy húron pendülnek.

     I have just had the chance to understand that the promise of the rich and the wager of a sick man are birds of a feather.

2. (idiomatic, colloquial, of friends or members of a group) they stick together, they are conspiratorial, thick as thieves

Most of the time it is used in a negative sense: They have the same reprehensible and wrong opinions and point of views.

(alike):

• egyformák
• egyik kutya, másik eb

(conspiratorial):

• összeszűri a levet