On today's Morning Joe, Mika Brzezinski, the host known for keeping the others in line, completely loses her composure after watching a satirical video mash-up from The Late Show With David Letterman mocking Dick Cheney. But Brzezinski's alone. The giggling is not contagious. Her co-hosts look on, confused. "What's wrong with you?" Joe Scarborough asks. The video wasn't even funny, the other panelists agree. The giggles continue, even through a segment nearly 30 minutes later. Try to keep a straight face while watching the clip above.