President Obama took to Twitter late Tuesday night to congratulate swimmer Michael Phelps on winning his 19th Olympic medal, and setting a new record for the most hardware earned by a single athlete.

Phelps responded to the President a few hours later. He used a lot of exclamation points.

Other celebrities whose congratulatory hi-hello's Michael Phelps retweeted include famed Lindsay Lohan ex-girlfriend Samantha Ronson, and what the LA Times identifies as "several professional poker players."

President Obama's Twitter bio notes that tweets sent directly from the Commander-in-Chief are signed "-bo."

President Obama's Twitter bio was written by his dog, Bo.

[LA Times // Image of Michael Phelps Rocking the Ganja via Star Magazine, though the original article is now impossible to find online. Here's a link to the RadarOnline homepage, which is where all the links to Star's Michael Phelps' story redirect]