महाभारत - कर्ण - अपातकानि पंच अनृतानि

विवाहकाले रतिसंप्रयोगे
    प्राणात्यये सर्वधनापहारे ।
विप्रस्य चार्थे ह्यनृतं वदेत
    पंचानृतान्याहुरपातकानि ॥

- महाभारत, कर्ण

vivAhakAle rati samprayoge
     prAnAtyaye sarva dhana apahAre।
viprasya cha arthe hi anRutam vadeta
    panchAni anRutAni AhuH apAtakAni ॥

- mahAbhArata, karNa

There are five instances when uttering a lie does not attract sin - during a wedding (to make it happen), romantic banter, when one's life is threatened, when you have lost all money and to help a (poor) brahmin.

- Mahabharata, Karna

[translator's note: http://wordsofwisdom.in/subhashitani/2010/07/28/]

भागवत - अनृतं जुगुप्स्तितम्

स्त्रीषु नर्मविवाहे च वृत्त्यर्थे प्राणसंकटे ।
गोब्राह्मणार्थे हिंसयां नानृतं स्याज्जुगुप्सितम् ॥

- भागवत

It is not a sin to lie under these circumstances - when talking to a woman, during a wedding, in your occupation, facing danger to your life, to protect a brahmin who accepts donation of a cow, to escape from violence.

- Bhagavata

महाभारत - आदि - अनृत

न नर्मयुक्तं वचनं हिनस्ति
    न स्त्रीषु राजन् न विवाहकाले ।
प्राणात्यये सर्वधनापहारे
    पंचानृतान्याहुरपातकानि ॥

- महाभारत, आदि

When a lie is told as a joke (to invoke happiness) it does not attract sin. There are four more circumstances in life when telling a lie does not attract sin. They are - when you are with a woman, during a wedding (so that a wedding may go on smoothly), when your life is in danger or when all your wealth is being stolen.

- Mahabharata, Adi, Lie