Orlando: The Obamas posted a video of themselves on Twitter promoting the Invictus Games, an international sports event for wounded, disabled and sick military personnel and veterans.
This image taken from a video, London, shows Michelle and Barack Obama on a call with Prince Harry and Queen Elizabeth II
"Careful what you wish for," the president says, as military officers stand with mock menace on their faces. British Royal Prince Harry, a patron of the Invictus Games, responded to the US president and his wife in kind.
He added a smiley-face emoticon and a video of his own, showing him chatting with his grandmother Queen Elizabeth while they thumbed through an Invictus Games brochure, just as the Obamas' challenge lands in his cellphone.
This image shows Queen Elizabeth II sitting with her grandson, Prince Harry looking at an Invictus Games brochure. Pics/AP
"Boom?" the Queen says to her grandson after watching the video. "Really, please!" she adds in amusement.
Harry smiles triumphantly, and says, "Boom!" The Invictus Games will take place in Florida from May 8 to 12.