A Polish Victory Lap is a cooldown lap by the winner of the race where the driver turns the car around (U turn) and drives forward in the opposite direction. The driver's side window faces the fans.
The first Polish Victory lap was first done by NASCAR great Alan Kulwicki after his first career Winston Cup victory at the Checker 500 (Phoenix International Raceway) in 1988. He celebrated his victory by driving a clockwise victory lap. A Ford engineer slapped him on the back and asked if that was a “Polish” victory lap.
Kulwicki celebrated his 1992 series championship by doing his only other "Polish" victory lap.
Kulwicki died in a plane crash on Thursday April 1, 1993 near Blountville, Tennessee. Two days after Kulwicki's death, Bristol Busch Series race winner Michael Waltrip honored his old short track foe by turning Kulwicki's trademark reverse "Polish Victory Lap" and then proposed to his wife in Victory Lane.  The next day Rusty Wallace followed Waltrip's lead, and every winner for the remainder of the season honored Kulwicki with a Polish victory lap. Wallace and 1993 series champion Dale Earnhardt carried #7 and #28 flags after the final race of the season at Atlanta for Kulwicki and the late Davey Allison respectively. 
Many local racetrack winners and series champions have saluted Kulwicki or his underdog spirit with a Polish victory lap, especially in his home state of Wisconsin. 2006 Milwaukee (Wisconsin) race winner Paul Menard (a Wisconsinite) celebrated his first Busch Series win with a Polish Victory lap.