asked senior adviser Eric Fehrnstrom what was the "most fun moment" he had ever had with Romney?

"I tell you, he's a closet prankster," Fehrnstrom explained. "I remember a trip he took as governor [of Massachusetts], one of the troopers who was assigned to his protection detail short-sheeted his bed."

So-called short-sheeting is a prank where bed sheets are folded in such a way that a person's legs can not extend to full length.

"The governor -- in order to turn the tables on this trooper -- sat down an composed a letter as if it had been written by the hotel manager, addressed it to himself as governor the the Commonwealth of Massachusetts, apologized for the bad housekeeping and the short-sheeting of his bed, and informed him that we have taken action to fire the chambermaid responsible," Fehrnstrom recalled.

"The governor showed that to the trooper that had short-sheeted the bed and of course his face went white," he added. "He was aghast that something like that had happened."

But instead of proving that the former governor has a sense of humor, the senior aide's recollection could actually reinforce the impression that Romney is insensitive about the struggles of working Americans.

At an event in January, the former Bain Capital executive declared that he liked “to be able to fire people.” He has also said that he found a story about his father closing a factory and laying off workers in Michigan to be "humorous."

"The biggest misperception is that he’s stiff," Fehrnstrom said on Saturday. "He’s got a great sense of humor."