The president ordered a hot fudge sundae for himself and a banana split for White House press secretary Jay Carney, according to press pool reports. He also teased that Carney has a serious sweet tooth.

"You guys are going to witness him eating the whole thing,” he said.

Obama, questioned by patrons about his ability to treat himself and still stay trim, echoed the first lady’s health-conscious advice about making it an “occasional” practice.

"I only have these once in a while," he said. "It's not a regular practice to have a hot fudge sundae."

He also offered to treat any one who hadn’t already paid.

"This is legal,” he joked. “I could not do this in front of a polling place, buy you ice cream. But I can do it here."

He wished one patron “happy birthday” and recorded a birthday greeting, by request, on another patron’s iPhone, according to the report.

Obama stopped at the University of New Hampshire Dairy Bar after a campaign speech at a nearby high school auditorium earlier in the afternoon. During the speech, he had noted that the auditorium was hot.