EXCLUSIVE: Christina Aguilera has pipes of steel, but her memory failed her on Super Bowl Sunday when she flubbed the ramparts out of the Star-Spangled Banner. With great gaffes come great amounts of criticism, and although the singer has tried to explain herself ("I lost my place"), she couldn't escape the wrath of Joan Rivers.

"How stupid can you get?" Joan asked when I talked to her on Monday. "Christina must have been thinking about food, that's why she forgot the words."

Before the big game, Christina belted out "What so proudly we watched at the twilight's last reaming" instead of "O'er the ramparts we watch'd, were so gallantly streaming." It was the second time she sang the "What so proudly" line, but before she used the word "gleaming" instead of "reaming."