Everyone knows a joke is less funny if you have to explain it. But if the joke wasn't funny in the first place, it's not really a problem. So, this week on the Best of Car Talk, Tom and Ray explain the origin of one of their favorites, a "full Chicago." In matters automotive, Caroline is concerned about her Toyota's low idle and her husband's insistence they wear bicycle helmets in the car for safety. Also, Sarah's car seems to have become a magnet for thieves and wayward trucks looking for something to hit; Bob is trying to imagine a life without power steering; Tom and Ray advise Jamie on how to fake a natural death for his Excel; and on Stump the Chumps we find out if John was triggering the Lardbutt Indicator in his wife's Golf. All this and more, this week on The Best of Car Talk.