from http://groups.google.com/group/comp.lang.python/browse_thread/thread/c41594596595e511/028422d707512283?#028422d707512283 (Alexander Schmolck), 2 counterintuitive ruby behaviors:
irb(main):001:0> [1,2].sort [1, 2] irb(main):002:0> [1,2].sort! [1, 2] irb(main):003:0> [1].sort [1] irb(main):004:0> [1].sort! nil ^^^ !!!
irb(main):017:0> x = 10 10 irb(main):018:0> [1,2,3].reject {|x| x < 2} [2, 3] irb(main):019:0> x 3