The #Pokemonmastersex meme refers to a viral marketing mishap that occurred in September 2020 during the first-anniversary rebranding of the mobile game Pokémon Masters to Pokémon Masters EX. To promote the update, the official Twitter account used the hashtag #PokemonMastersEX, but the lack of capitalization caused users to instantly misread it as 'Pokemon Master Sex.' The hashtag trended globally within hours, sparking a massive wave of fan art, jokes, and disbelief as the internet collectively mocked the unintended adult connotation. It remains one of the most famous examples of 'hashtag horror' in social media history, frequently cited as a cautionary tale for marketing teams and a beloved trope for fans of the franchise.