Former President George H.W. Bush and former first lady Barbara Bush delivered a witty address at George Washington University's commencement Sunday.

The parents of President Bush received a standing ovation before and after their routine from a crowd of about 25,000 on the National Mall, The Washington Post reported. About 4,500 of the nearly 6,500 graduates looked on as they were awarded honorary doctorates in public service.

"I'm sensitive about the age thing," said Mrs. Bush. "Once when I was speaking, a girl went home and told her mother, `I heard the mother of the president of the United States — George Washington."'

Her husband retorted: "I consider that an honest mistake. After all, you look like George Washington."

The former president dusted off one of his most famous bits, recalling a speech by South African Archbishop Desmond Tutu as "so-so."

The Bushes delivered a serious conclusion.

"Time is the capital from God that is yours to invest," George Bush said. "How will you invest that? With more massive projects under tight deadlines? By playing video games? You'll get a lot more satisfaction by tucking a child into bed, seeing a victim of Hurricane Katrina moving back into their home. It's best to invest in the lives of people."

University President Stephen Joel Trachtenberg said the visit was the result of an invitation he extended to George Bush in 1991.

"At the time, he said he would give my request to his schedulers and get back to me. It took 15 years, but he kept his promise," said Trachtenberg.

Despite the background of the keynote speakers, the ceremony was generally free of politics, with only a handful of protesters. One woman was escorted away after she ignored warnings to close a pink umbrella with a sign reading "No More War." A pair of graduates who taped the peace sign on their mortar boards stood throughout the speech with their backs to the Bushes.