A new TikTok trend has emerged in which leftists playfully threaten to “kneecap” anyone who doesn’t support Black Lives Matter. Clips uploaded to the Chinese-owned website show users, most of them young women displaying LGBT colors, dancing while miming to the words, “If you don’t support Black Lives Matter, I’ll break your neko-neko-kneecaps.” Neko is the Japanese word for cat, which...