#42 asks #43: How are you not on Twitter?

Former President Bill Clinton late Monday ribbed former President George W. Bush over the 43rd president's lack of a presence on Twitter.

Clinton used the hashtag #HowAreYouNotOnTwitter? in a Presidents Day message to Bush, President Obama and former Presidents George H.W. Bush and Jimmy Carter.

The message was retweeted by Obama's Twitter account.

Clinton was in Haiti with Clinton Foundation partners viewing agricultural and environmental projects.