Bill Clinton and George W. Bush may be an unlikely pair of friends, but the two appear to be closer than most would think, especially with their exchange of comical social media messages Wednesday.

Clinton, 68, announced via Twitter that he received “41: A Portrait of My Father,” Bush’s book about former President George H. W. Bush. He made sure to point out that he couldn’t send the tweet directly to Bush because the 43rd President doesn’t use Twitter.

"Received my copy of #41 by #43, George W. Bush," Clinton tweeted along with a photo of himself reading it. "Touching tribute! #HowAreYouSTILLNotOnTwitter #PresidentialTweeters."

Bush, 68, responded with the social media platform he does use – Instagram.

"Thanks, 42! Hope you like the book about your pal, #41," he wrote along with a screenshot of Clinton's tweet. He also added the hashtags: "#HowAreYouSTILLNotOnInstagram #PresidentialGrammers #BrotherFromAnotherMother."

Bush and Clinton previously showed off their bromance when they announced their Presidential Leadership Scholars Program in Washington in September.

"I will say one thing nice about my friend here - I'll say more than one thing but this particular one thing - he used to call me twice a year in his second term just to talk," Clinton said during the event. "We'd talk - depending on how much time he had because he was busier than me - somewhere between 30 and 45 minutes for several years and it meant a lot to me."