Barack Obama makes cameo appearance at Michelle’s book promo

US former President Barack Obama made a surprise appearance here at an event where wife Michelle Obama was talking about her just-released memoir, “Becoming.”

“This is like - you know when Jay-Z comes out during the Beyonce concert?,” he said as he emerged on stage at Washington’s Capital One Arena to present the former first lady with a bouquet of flowers.

The thousands attending Saturday night’s event stood and cheered on seeing the former president.

Moderator Valerie Jarrett, a long-time friend of Michelle Obama who served in the Obama administration, introduced Barack as a “special guest.”

She then asked him to recount his first encounter with Michelle at the Chicago law firm where they were both working.

“First of all she’s really tall and most of it was legs,” Barack Obama, prompting his wife to respond in mock outrage: “There are children here!”

“I’m just saying ... it was impressive,” Barack replied, before going on to describe his wife as “extraordinarily smart” and “beautiful.”

Michelle Obama launched the book tour on Nov. 13 in her native Chicago. The moderators for future stops will include writer Chimamanda Ngozi Adichie and actresses Reese Witherspoon and Sarah Jessica Parker .