"When I was a boy, I used to think that becoming rich and becoming famous would make me happy," he told a St. Patrick's Day political breakfast in south Boston on March 20, 2005.
"Boy, was I right!" he laughed.
His videotaped joke, surfaced by the BuzzFeed website Tuesday, was his final laugh line of a joke-filled breakfast that included other back-and-forth remarks about his wealth.
State House Speaker Salvatore DiMasi earlier joked Romney must have enjoyed the short ride from Logan International Airport to the convention center. He then looked at Romney and said: ''Are those tickets in your pocket? I don't want to keep you too long. You can leave any time you want."
Romney replied, ''I'll be here until you get funny," The Boston Globe reported at the time.
DiMasi, a Democrat, shot back: ''You being president of the United States. That's a joke," the Globe said.
Boston Mayor Thomas Menino quipped Romney must be a big sports fan because he has season tickets for all the Boston Celtics basketball games -- all the out-of-town games, that is.
Romney -- looking less gray than he does in 2012 and wearing an Irish-theme boutonniere -- began his own remarks with, ''It's great to be here in Iowa this morning." Then feigning a mistake, he said: ''Oops. Wrong speech. Sorry about that."
He said that when he became governor in 2003, he "got some advice from some big-time Massachusetts pols. My favorite came from the auditor, [who] pulled me aside and said: 'Listen, you need to know something about Massachusetts Democrats. Massachusetts Democrats are honest. When they're bought, they stay bought.'"
Romney also explained he was against same-sex marriage because as a Mormon, he believed ''marriage should be between a man and a woman -- and a woman -- and a woman."