I had to post this, I did like the idea of someone fondly remembering their semester abroad with some funny in-jokes on pin-back badges, and she is selling them too at US$2.00 each!

http://www.berkeleybeacon.com/2018/10/16/junior-turns-emerson-inside-jokes-into-buttons/

Rogulina said she created buttons when she couldn't find the types of designs she wanted.

Of course, I must mention (again) these are called buttons in the USA & Canada.