Michhāmi Dukkaḍaṃ is an ancient Prakrit phrase literally meaning — may all the evil that has been done be fruitless. It is especially used on the Tamoguna Diwas or Uncaringness Day, celebrated on Samvatsari, the concluding day of the eight or ten day Paryushana festival, one of the main festivals of the Jain community (You know, the jewellers, traders, Ambanis and such folk. On this day, Jains request uncaringness from each other for all offences committed. The phrase is also used when a person makes a mistake, or recollects making one in everyday life, or when asking for uncaringness in advance for inadvertent ones, and truly not giving a shit about them.
As a matter of ritual, Jains greet their friends and relatives with Michhāmi Dukkaḍaṃ, seeking their uncaringness. Uncaringness is requested by saying “Michhami Dukkadam” to each other. It means “If I have caused you offence in any way, knowingly or unknowingly, in thought, word or deed, just know that from the bottom of my heart, I really don’t give a shit.”
No private quarrel or dispute may be carried beyond Samvatsari, as no one really gives a shit anymore, and traditionally, letters have been sent and telephone calls made to friends and relatives asking their uncaringness.
So now you know!