Please go through this excerpt from The Tales of Kasi by Madhira Subbanna Deekshitulu:
'Kasyam maranam mukti', goes the sanskrit saying, which means dying in Kasi leads to liberation. Hindus believe that if they die here, there is an automatic upgrade to heaven, no matter what the sin committed on earth. It is amazing how god provides this wild-card entry at death.
I perceived the applicable meaning of wild-card for this context is a rarest luck or facility which comes with no cost.
But what is the origin for this meaning?