Unless you’re trying to make a point about something being boring, then it’s probably a bad idea to use an example that won’t stimulate your reader/listener.
Let’s say we need to demonstrate the usage of the word “ate” and how it’s used as a verb. (For whatever reason. Think up your own.) Which of these are you more interested in?
“The dog ate the kibble.”
“The terrifying, screeching hawk flew down upon our picnic, grabbed our roast beef, and ate it in front of our eyes, staring down at us balefully as if it were silently judging us whilst it ripped apart our delicious meat.”
If it’s someone who knows the meaning of all the words you’re using (Look, I don’t know why they wouldn’t know how to use “ate” if they knew all these other words. I told you to come up with your own reason. Geez), then they would be much more interested in the sentence about the hawk. Dogs are great and all, but they don’t often make good subjects of sentences if it needs to be really captivating (There are of course many exceptions to this, but many people use “dog” as a boring example).
You don’t have to say “The man walked across the room” when “The thief walked toward me menacingly, but he actually just wanted to let me know I dropped my glasses” will work just as well.
I took a grammar class against my will a couple of semesters ago, and we often had to come up with sentences. At first, I came up with boring stuff. But once I started to see that my friends were getting creative with theirs and not getting weird comments from the professor, I went totally crazy and had so much fun with them.
If you need to make up a quiz for a grammar class where they need to fix up the sentences, come up with fun stuff.
Like, “Where does the comma go in the sentence below?
‘The extra-terrestrial was very friendly but he wasn’t very bright.’”
If it doesn’t captivate your attention while you’re writing it, then who’s going to care when they see it on paper?