What do you do when the debt ceiling is lifted?

Spend money, of course.

A day after signing the $2.4 trillion deficit reduction package into law, President Obama took his budget staff out to celebrate — with a lunch at Good Stuff Eatery on Capitol Hill. The restaurant is owned by Spike Mendelsohn, who appeared on the TV cooking show “Top Chef.”

The aides included Jack Lew, the budget director; Rob Nabors, director of legislative affairs; Ann DeParle, deputy chief of staff for policy; Bruce Reed, chief of staff to Vice President Biden; and Gene Sperling, director of the National Economic Council.

Obama seemed in good spirits, announcing to the cashier that he would treat not just for his staff’s lunch but also for the meal of a woman standing next to them in line.

“It smells good,” he said told customers on the second floor, according to a press pool report distributed to reporters. “Michelle eats here all the time, but I don’t get out.”

The group took a seat at a table next to a window, and there was plenty of laughing and backslapping — literally, Obama patted Nabors on the back. Some customers approach the president to shake his hand.

“He asked us if he had finished our burgers,” Nora Bessey, an intern at the copyright office.

Obama offered Andrew Parker, 11, a choice of milkshakes on the White House staff’s table.

“Choose any milkshake,” the president said, according to the boy. “I guarantee this table isn’t going to drink them all.”

Not surprisingly for a Capitol Hill lunch joint, Obama couldn’t avoid mingling with fellow politicians. Rep. G.K. Butterfield, a North Carolina Democrat who was passing by, stopped in for a brief chat with the president.

“We talked about the difficult vote the other night,” he told reporters outside. “I explained to him that I didn’t vote with him, but I’m glad that it passed. He said he understood.”

When the group left, crowds around the restaurant yelled “Obama!”

The celebration is only the start for the president, who will fly Wednesday afternoon to Chicago for a pair of birthday party fundraisers at the Aragon Ballroom. He turns 50 Thursday.

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