whiskey plate
n.— «Odds are you’ve seen cars carrying plates bearing the telltale W. Some still wonder what that lone letter designates while others think they know exactly what it means. While those plates are colloquially referred to as “whiskey plates,” and they are indeed primarily given to drivers with multiple DUIs, Evans insisted the letter W was assigned randomly.» —“Good Question: All About License Plates” by Ben Tracy WCCO-TV (Minneapolis, Minnesota) Aug. 14, 2007. (source: Double-Tongued Dictionary)