World's richest man Elon Musk tweeted, "Zuck is a cuck," in response to Meta CEO Mark Zuckerberg reacting with a laughing emoji after Wendy's suggested on Threads that he should go to space "just to really make (Musk) mad". Meta launched the Twitter rival app Threads last week. In another tweet, Musk wrote, "I propose a literal d**k measuring contest."