It was a unique event for the United Nations laced with nostalgia, humor and tributes the secretary-general and the US president toasting each other for the last time in front of the world's leaders. Every year, the UN chief hosts a formal lunch for the presidents, prime ministers and potentates attending the annual ministerial meeting of the UN General Assembly. And every year, the US president responds as representative of the host country on behalf of the leaders. But Secretary-General Ban Ki-moon said yesterday's lunch was unique.

"Never before have a president of the United States and a secretary-general of the United Nations completed their terms at about the same time within just 20 days of each other." Ban then looked at Barack Obama, sitting just a few feet away at the head table, and said: "Mr President, we need to find something to do!"

The secretary-general's second five-year term ends Dec. 31. Obama leaves the White House on January 20 after eight years. "I challenge you to a round of golf," said Ban, whose whirlwind globe-trotting schedule doesn't give him much time to play. "But please don't challenge me to a game of basketball!" Obama, a golfer and avid basketball player, didn't say whether he would take up the secretary-general's challenge ' or what his future plans are.

Neither did Ban, who repeatedly refuses to say whether he will run for president of South Korea, where he was foreign minister before taking the helm of the United Nations.