Ruby's one line guideline

I was doing some development in Ruby today and noticed that I was using this guideline often to detect Ruby code-smells: If I wrote more than one line of code to do something that takes 5 lines of code in Java, then I must be doing something wrong. Following this guideline over and over taught me many Ruby tricks. Try it and let me know what you think. Otherwise, if you know other guidelines, please let us know what they are in a comment.