The Trap Card meme originates from the Yu-Gi-Oh! trading card game and anime series, specifically referencing the dramatic moment when a player reveals a hidden card to counter an opponent's move. The iconic catchphrase 'You've activated my trap card!' became a viral sensation in the mid-2000s across forums like 4chan and Reddit. It is typically used to signal that someone has walked into a pre-planned setup or to highlight a sudden, unexpected reversal in an online argument. While often featuring the original card art or characters like Yugi and Kaiba, the format has evolved into a versatile way to celebrate any 'gotcha' moment.