The story
From a video titled "Get Mario Karted" uploaded to YouTube by user HowBoutGaming in June 2014 wherein the player was hit by multiple items very close to the finish line and got last place.
Etymology from Wiktionary, CC BY-SA 4.0.
get Mario Karted
Today it means: To suffer a sudden and often extreme loss of advantage, especially when nearing a conclusion or when due to luck-based factors. Full definition →