Big dumb action movies are a dime a dozen each summer. But really good big dumb action movies - thinkPredator, Speed, and Independence Day - are rare indeed. So when one of them comes off the Hollywood assembly line and zaps your brain's less discerning pleasure centers, attention must be paid. Which brings us to Fast & Furious 6 - a borderline ridiculous, over-the-top demolition derby that also happens to be a perfectly constructed low-IQ blast.