Once a year back in high school, we had a fundraiser called TAG DAY. For a dollar each, students could buy small, printed tickets (i.e. tags) and present them to other students, who would then have to do whatever the tag presenter asked him or her to do.
We also had a HIGH SCHOOL GYMNASIUM.
For someone who speaks both English and German, those two phrases are redundant. TAG means DAY in German and instead of attending HIGH SCHOOL, Germans go to a GYMNASIUM (pronounced gim-nozium).
