I second the Billy Fucillo's commercials. I get it, man; we can save a lot if we buy a crappy car from you. You're just scaring away the customers by yelling at them like that.
Since I'm on the topic of yelling, I must bring up the Oxy-Clean commercials. The guy is advertising a cleaning agent, for crying out loud; does he really have to shout like he's trying to be heard over Niagara Falls? And I can't imagine why he'd be really, really happy about showing us how shiny this stuff can make pennies. Pennies are useless, anyways. They're just good for taking up space in your wallet and making tip jars look full. Why make 'em really shiny?
And anything with a Geico caveman annoys me. They don't yell in some of the commercials, but they're grating, anyway.