Ever have a teacher who tried way too hard to be "down" with the kids? Who never knew that he was using out-of-date lingo or patronizing the intelligence of the people he wanted to befriend? If you have a masochistic desire to spend hours with that kind of person, you could tune into Current TV, a new cable channel that debuted in 20 million homes nationwide Monday. (In South Florida, Current is available on DirecTV.) For a channel that is supposed to be aimed squarely at 18- to 34-year-olds and reflect their views and concerns, Current (whose chairman is Al...