Bush, Clinton poke fun at each other on social media

Two former presidents are having a little fun with each other on social media.

Former President Bill Clinton posted a tweet of himself reading George W. Bush's new book with a hashtag #howAreYouSTILLNotonTwitter?

So Bush replied on Instagram with "Thanks, 42! Hope you like the book about your pal, #41. #HowAreYouSTILLNotOnInstagram #PresidentialGrammers #BrotherFromAnotherMother"

We're pretty sure that's the first time two former presidents have referred to themselves as brothers from another mother.