1 definition by alfbon

To remove a muck sack by unsticking one's balls from the inside of one's legs. This is generally done by hand or by spreading the legs, and is widely regarded as one of the best feelings in the world.
Person 1: Wow I feel amazing!
Person 2: Why?
Person 1: I just shillacked one of the strongest muck sacks of my life.
by alfbon February 7, 2018
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