What lays under Holden's furious reaction to Sally after she says "We'll have oodles of time to do those things"?
Chapter 17 of J.D Salinger’s The Catcher in the Rye shows Holden Caulfield during one of the many personal conflicts that he tends to fall into each time the idea of adulthood intermingles with his reality as a young adult.
This time, he is with Sally. Holden, in one of his many hormonal rants, tells Sally how he hates New York, the city life, and every aspect of what he sees every day. Remember that Holden feels that everything that is not like himself is "phony". He also tells Sally that he would much rather live in the woods, and this is when he proposes an interesting idea: he tells Sally that they could get whatever money they have, drive to New England, and then get married and live in a cabin in the woods until their money runs out.
Sally says that, after college, they can do all that and that they will have tons of time to do it. However, here Holden gives another rant about how married people never have time to do anything. Basically, what he says is that married life and social expectations are so delineated and stern that life becomes nothing but the constant application of a specific routine.
However, Holden notices then that he is contradicting himself. How come he wants to marry and move away when he has just said that this is a boring and phony life? Again, Holden has an argument, but no clue on how to support it.
I said “no”, there would not be wonderful places to go after I went to college and all. Open your ears. It will be entirely different. We ‘d have to go downstairs in elevators with suitcases and stuff. We’d have to phone up everybody and tell’ em good-by and send’em postcards from hotels and all. And I’d be working in some office, making a lot of dough, and riding to work in cabs and Madison Avenue buses, and reading newspapers and playing bridge all the time, and going to the movies and seeing a lot of short and coming attractions and newsreels.
Holden's wrath is nothing but another fall into his reality: he realizes that his idea may sound mature and quite fantastic, but it is actually a silly and immature idea. This is a direct conflict between how Holden feels (he thinks that he is ready for bigger and better things), and what he THINKS that he feels. For, now, he sees how his constructs on adulthood are completely wrong- but so are his ideas of youth! The wrath is brought up by how lost he feels in a world that he obviously cannot understand, and where he has not yet found a niche. That, combined with the fact that it is Sally (or all people) who brings him to this realization, is enough to set him off quite easily.