From the beautiful toilets of my (now former) school.

When the students here graduate, there are certain old traditions.
One of these involve writing in your classmates' student caps, as seen on the picture.
You also have to write the last exam grade you get in the middle, and your two best friends leave their teeth marks on the brim of the cap.
Oh, and if you party 'till the sun rises, or throw up because of alcohol-related imbibing, then your friends cut certain marks in the brim as well.