All the fun presidential banter seems to be happening online.

On Wednesday evening, social media lit up after former President George W. Bush sent an incredible retort when another ex-president, Bill Clinton, questioned him on why he wasn't on Twitter, Washington Post reported.

"Received my copy of #41 by #43, George W. Bush. Touching tribute! #HowAreYouSTILLNotOnTwitter #PresidentialTweeters," Clinton tweeted along with a photo of himself reading "41: A Portrait of My Father," Bush's new biography of his dad, former President George H.W. Bush.

While the senior Bush, to whom the book is dedicated, is on Twitter, Bush Jr. has not yet joined the online social networking service.

So instead, Bush chose to respond on another social media site, Instagram, where he asked why Clinton didn't have an Instagram account, according to Huffington Post.

The most awesome part: he included the hashtag "#BrotherFromAnotherMother," which could probably be the first time two former presidents have referred to themselves as brothers from another mother.

"Thanks, 42! Hope you like the book about your pal, #41. #HowAreYouSTILLNotOnInstagram #PresidentialGrammers," Bush replied to his predecessor by reposting the tweet on Instagram.

The conversation seems even more incredible knowing that both Bush and Clinton could find themselves involved in the 2016 presidential race since "Clinton's wife, Hillary Clinton, is widely considered the Democratic frontrunner and there is mounting speculation Bush's brother, former Florida Gov. Jeb Bush, could run on the Republican side," according to Business Insider.

Meanwhile, there have been various other instances where we have been warned that engaging in a comical war of words with a politician on social media might not be the best idea.

Just before Halloween, Madeleine Albright also responded hilariously to comedian Conan O'Brien's costume idea, leaving the 51-year-old host delighted at starting his "first Twitter war."

"I picked out my Halloween costume. I'm going as 'Slutty Madeleine Albright,'" O'Brien tweeted.

"I'm considering going as hunky Conan O'Brien - but that might be too far-fetched," Albright had responded.