hi raghy sir,Greetings.
In the villages sometimes someone would 'donate' a cow or bull to one of the temples ( usually bull). They would let the bull loose after sprinkling tumeric water and/or other ceremonial water ( like water from the 'kalasam' etc). Then the 'ex-owner' wouldn't pay attention about it's actions. I think 'thanni thelichu vidaradhu' originated from that.
Cheers!