GEORGE W. BUSH, BILL CLINTON: Social Media Flame War

Former presidents George W. Bush and Bill Clinton got into it on Wednesday, but they weren't arguing politics or foreign policy or economics. They were jabbing each other over which social media service is better.

Clinton got the game going by tweeting a photo of himself reading 41, Bush's new book about his father, former president George H.W. Bush. He called the biography "a touching tribute" and ended his message with the hashtag "#HowAreYouSTILLNotOnTwitter."

The younger Bush fired back a bit later on Instagram. He posted a screenshot of Clinton's tweet, thanked him for the kind words and completed it with the hashtag "HowAreYouSTILLNotOnInstagram."

Source: ABC News