Following are a number of back-translations as well as a sample translation for translators of Ecclesiastes 10:20:

• Kupsabiny: “A person should never backbite a king or think it in his stomach, nor abuse a rich man in the bedroom. A bird may take those words to those people.” (Source: Kupsabiny Back Translation)
• Newari: “Do not speak contemptible words against the king, even in your thoughts,
  or abuse a wealthy man by cursing him even in your own room.
  For perhaps a bird flying in the sky
  might go and tell the words that you have spoken.” (Source: Newari Back Translation)
• Hiligaynon: “Do not curse the king even in your (sing.) thoughts, or the rich-one even in secret, for there might be-(someone) who could-tell it to them.” (Source: Hiligaynon Back Translation)
• English: “Do not even think about cursing the king,
  or cursing rich people, even when you are alone in your bedroom,
  because it is possible that a little bird will hear what you are saying,
  and tell those people what you said about them.” (Source: Translation for Translators)