Step 2: Change "Autocorrect" settings
1. Open up Microsoft Word or Outlook and find the Autocorrect settings in options (the location of it varies depending on which version you have).
2. You can choose any word to be replaced by any other word you may want. For example, you can chose to have the word "the" replaced by the word "idiot".
3. When you have created an autocorrect rule, click the Add button and then click OK.
Now when anyone types the word "the", it is going to be replaced by "idiot" automatically. To remove this prank, just remove these rules from the autocorrect settings.