Mr. and Mrs. McArdle are basically caricatures of American tourists. In particular, Mr. McArdle's character is an exaggeration of a stereotypical consumerist, loud American. Essentially all his dialogue, which is limited to the first few pages of "Teddy," has to do with yelling at his son in order to protect his expensive possessions: first his Gladstone (which he forcefully explains cost him twenty-two pounds), and then his Leica camera. Salinger rather deftly characterizes Mr. McArdle with, among other juicy lines:
Mr. McArdle played leading roles on no fewer than three daytime radio serials when he was in New York, and he had what might be called a third-class leading man's speaking voice: narcissistically deep and resonant, functionally prepared at a moment's notice to outmale anyone in the same room with it, if necessary even a small boy. When it was on vacation from its professional chores, it fell, as a rule, alternately in love with sheer volume and a theatrical brand of quietness-steadiness. (1.1)
Like Nicholson, Mr. McArdle is defined by visceral, almost gross physicality. His "sunburned, debilitated-looking body" is "lying supine, in just the trousers of his pajamas" (1.1). Later we catch a glimpse of his "nude, inflamed-pink, right arm" (1.1). Unlike Teddy, whose domain is that of the spirit, Mr. McArdle is defined by and confined to his earth-bound body – just like Nicholson and his heavy thighs.
Both Mr. and Mrs. McArdle (whom Salinger spends even less text on) are examples of the American lifestyle that Teddy finds to run counter to spirituality. Later he says to Nicholson:
"…it's very hard to meditate and live a spiritual life in America. People think you're a freak if you try to. My father thinks I'm a freak, in a way. And my mother – well, she doesn't think it's good for me to think about God all the time. She thinks it's bad for my health" (4.73).
Because we've already spent a little time with the McArdles, readers know exactly what Teddy is talking about by the time they get to this passage. And because Salinger makes the McArdles into such caricatures, readers are driven to take Teddy's side against his rather ridiculous parents, even though the majority of those readers are consumerist, apple-eating Americans themselves.