Well, long story short, I never had the guts to actually mess with someone like this, but when I became a teacher, I started grading papers digitally and found myself writing the same statements over and over again, despite the fact that each of the students' writing was quite different from one another. I then remembered my idea for a prank and thought I could use it for good!
Once you're there, you can go to Proofing, which will open up the following menu (see below).
You want to click on AutoCorrect options, and that will give you a menu like the picture below. If you select a paragraph of text beforehand, then it will automatically populate the field as seen below. For example, I wanted to be able to say:
In wh-clauses, do not invert the subject and the auxiliary:
Correct: "I didn't know what I should do."
Incorrect: "I didn't know what should I do."
So I typed that into a comment box, selected the text, then went to Word Options --> Proofing --> AutoCorrect Options. I then typed in that I want MS Word to replace "whc" with this paragraph (the code you select doesn't matter, as long as you can remember it--I chose whc for wh-clause). You can see this below:
Every semester I learn something new about grading digitally, and I'm always looking forward to any new ideas you may be using. Feel free to leave a comment below.
Have a good one, and good luck out there!