​​TO VANISH INTO THIN AIR — to disappear suddenly in a mysterious way.

They can’t just have vanished into thin air.
Они не могли просто исчезнуть.

vanish ['vænɪʃ] — исчезать, пропадать.

#idioms #vanish

​​A PIG IN A POKE is a thing that is bought without first being inspected, and thus of unknown authenticity or quality. (Wikipedia)

authenticity [ˌɔːθen'tɪsətɪ] — аутентичность, достоверность, подлинность.

#idioms