Joke Collection Website - Bulletin headlines - What is the stem of the library cup standing on the edge of the table?

What is the stem of the library cup standing on the edge of the table?

This stalk means:

The cup makes a sound when it falls.

Prevent water from overflowing from the cup that is not tightened.

The source of this stalk:

Contemporary college students will put a cup on the table in order to occupy a seat, which is easily satisfied.

The usage of this stalk:

You can use this to remind people when they are seated.