To take a steel or other hard metal screw or bolt and cross thread it into a softer metal such a aluminum. Most often found after purchasing a used machine the first time you attemp to remove any bolt or scew.
I just bought this dirt bike for pretty cheap but I found out they applied "Perry County Loctite" to nearly every bolt on the machine.

Alternatively, "Boy will they be pissed when they find out I applied Perry County Loctite to that head bolt on that car before I sold it on Craigslist"!
by Perry County Resident January 5, 2012
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