Thank you for the answer! Is the phrase still in use?

🌝Yes, it is widely used

++Elena

Does it really mean God knows what?

Yes, if it's not negative, "God knows what" is correct

¿So you could use it in: “I wouldn’t drink that if I were you - he could’ve put God knows what in that coffee.”

Exactly!

Would you mind translating this into Russian so that I can see it in action?

На твоем месте я бы не стал это пить. Он Бог весть что мог туда намешать. ( Но я бы сказала " неизвестно что мог намешать". Не знаю, почему)

👍🏼😉🖐🏼

🙋