Ronald McDonald and Grimace.Eugene Gologursky/Getty Images for Macy's, Inc. After McDonald's joked about Tesla accepting a fake "grimacecoin," real versions started trading. One of them surged more than 285,000% in the hours after the tweet from McDonald's, CoinDesk found. At least 10 other versions came to fruition following the Twitter exchange. Sign up here for our daily newsletter, 10 Things Before the Opening Bell. McDonald's response to Elon Musk's push for the fast-food chain to accept dogecoin caused a new cryptocurrency called grimacecoin to surge more than 285,000%.