![drink coaster](https://popgoesthepage.princeton.edu/wp-content/uploads/sites/152/2017/03/drink-coaster.jpg)
12. Drink Coaster [c.1980] These hard, plastic squares act as coasters for cold or hot Muggle drinks. Interestingly, they contain a hidden function. Retract the silver slider, and a space for storing small scraps of paper is revealed. We postulate that this was a popular way for Muggle students to pass notes in class (and keep beverage rings from staining their desks).