A whiskey thief is a tool that master distillers use to extract small portions of whiskey from an aging barrel for sampling or quality control.
[1] The old-fashioned ones are made typically of copper and resemble a drinking straw in design.
[2] It has a coned narrow hole at the bottom and a vent hole at the top in which a distiller can cover with the thumb once the device is inserted in the barrel to trap and lift the whiskey out.
[3] By removing the thumb from the upper vent hole, the whiskey is released to drain into drinking glasses for tasting.
[2] Newer models may be made of clear plastic or glass with the larger models having the capability of accepting a hydrometer for testing purposes.