YOU SAID:

I'll believe it when pigs start flying.

INTO JAPANESE

豚が飛び始めたら信じます。

BACK INTO ENGLISH

Believe when the pig begins to fly.

INTO JAPANESE

豚が飛び始めると信じてください。

BACK INTO ENGLISH

Believe that pigs begin to fly.

INTO JAPANESE

豚が飛び始めると信じてください。

BACK INTO ENGLISH

Believe that pigs begin to fly.