At this point, midway through its fifth season, Lost is about as consistently good as it’s ever been. It’s not hitting the highs its capable of (no episode this season rivals anything like “The Constant” or “Walkabout”), but it’s also not sinking into the really stupid lows it used to alternate those highs with. It’s just a fun, poppy show, a blend of pulp, goofy sci-fi and basic character drama. I don’t know how long Lost can keep this up, but episodes like “Namaste,” written by Brian K. Vaughan and Paul Zbyszewski and directed by Jack Bender, have been among the most unbridled fun you can have watching TV. Lost, at its best, is just a terrifically good time, and “just a terrifically good time” describes most of Season Five to a T. When a title came up early in the episode reading “Thirty Years Earlier,” it made me giggle with glee because, c’mon, where else are you going to see that on a TV show?