Travis Winters showed me a nifty trick to reference to previous line in rib by using the symbol _ (aka underscore). Look at the example below:
$ irb ruby-1.9.2-p290 :002 > "hello world" ruby-1.9.2-p290 :002 > @hello = _ ruby-1.9.2-p290 :002 > puts @hello hello world => nil
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