''Stupid, stupid, stupid!'' Hugh Laurie chants over and over, his eyes closed. The actors around him try to give the star as much space as they can in this tightly staged elevator scene. Is he throwing a tantrum? Engaging in a moment of self-castigation? Hardly — he's practicing. The line he's supposed to deliver to his team of underlings, Kutner (Kal Penn), Thirteen (Olivia Wilde), and Taub (Peter Jacobson), is this: ''Tell her that the thing about emotional reactions is that they're irrational — or stupid.'' But for some reason, ''stupid'' isn't coming out American enough to the British star. ''It just doesn't sound right,'' he says. The camera rolls, the director calls ''Action!'' Again, to the untrained ear, Laurie's ''stupid'' sounds about as Yankee as baseball. ''Nope, one more time. Sorry.'' Surely, eight episodes into House's fifth season, the actor who's won two Golden Globes playing Dr. Caustic can relax about two tiny syllables? ''The accent is the most frustrating thing for me,'' Laurie says later. ''Almost everything else you do in life gets easier the more you do it. This one doesn't.''