One time in 5th grade, I had this teacher who gave us all bottles like this and she told us to squeeze it all out and, of course, we were like "fuck yeah" and did it. Then she said, "Now, try and shove it all back in the container." Of course, we all tried, and then stared at her confused. When we all obviously gave up, she said:
"In the moment, you were so consumed with what you were doing that you didn't realize the mess you were making. Then, after it was so quickly and easily poured out, you realize it is impossible to put it all back in. Remember this for the rest of your lives when it comes to the words that come out of your mouth."
We were something like then years old. But somehow, to this day, I think of it constantly.