Go into Google Docs, start up a new spreadsheet. In cell A1 enter “Red”, and in A2 enter “Green”, and in A3 enter “Blue”. Now, select all three cells. While holding the CTRL button click on the lower right corner of the selected cells and drag down.
Now try it with Superman/Batman/Spiderman… or Basset/Terrier/Daschund… or, to get really interesting, Brad Pitt/Hugh Jackman/Angelina Jolie.
This little hint blatantly stolen from this lifehacker post.