tweaker's dozen
A quantity of eleven (11). It comes from the TV show COPS, where the description is a dozen minus the one that the tweaker kept for himself. Usually in reference to ounces of drugs.
The drug dealer showed up with a tweaker's dozen of meth. His behavior made it obvious where the other ounce of meth was.
Oregon tweaker’s dozen
An all encompassing unit of measurement that is one less than the prosecutable amount.
A woman with 38 pills of oxy is one short of an Oregon tweaker’s dozen. (40 being the prosecutable amount)