Definition

An acronym for 'Windows Down 55 mph'—the free air conditioning hack favored by drivers of older cars without functional AC systems. Roll down all the windows and drive fast; problem solved.

Example Usage

My ancient VW Bug's AC is broken, so I'm going with WD55 all summer.

Source: Urban Dictionary (https://www.urbandictionary.com/define.php?term=WD55&defid=864)