Elon Musk has sold around $5 billion of Tesla stock as part of some kind of in-joke with his Twitter followers about whether he should pay taxes. On Saturday, the Tesla CEO polled his Twitter followers about whether he should sell 10 percent of his stake in the company, noting in a tweet: “Much is made lately of unrealized gains being a means of tax avoidance.” Twitter users ruled that he should sell off the stock and, this week, he sold roughly 3 percent of his holdings—far short of the promised 10 percent, though there may be more to come. However, obviously, the poll did not determine the sale. Musk said in September that he’d sell off a chunk of stock by the end of the fourth quarter because of options that were due to expire early next year, and The Wall Street Journal reported that some of this week’s sales were made under a preset trading plan Musk set up on Sept. 14, nearly two months before he polled his followers. As of Thursday morning, the billionaire hasn’t explained why he sold off the stock.