The 38th parallel on the bed

This thing reminded Yaku of the "38th parallel" from his childhood. I wonder if any of you have experienced it? At least people like me who are a certain age remember it vividly. Back then, we were all so young, so innocent, so naive about each other, so awkward around each other, and in many ways, so abnormal. Boys and girls were seated together at one table, and to clearly demarcate our boundaries with the little girl next to us, we would draw a "38th parallel" on the desk. Whenever you were focused on your homework and accidentally crossed the line, someone would kindly remind you with extreme measures — like poking you with a compass: "Hey, you've crossed the line!!"

Now, some people have even drawn the "38th parallel" on their bedsheet. Is it because they didn't get enough of this game as kids? Or did they endure so much torment from their desk partners that it left a deep psychological scar? I wonder what it feels like to sleep on such a bed? Waking up in the middle of the night to someone shouting: "Hey, you've crossed the line! Go back to your side!!"