I'd just finished my last class of the day, turned off all the electric stuff in my classroom and was about to leave, locking the door behind me, when two of my co-teachers came in speaking Korean to each other. One of them turned the lights back on while the other started moving furniture. Still speaking only Korean and not having addressed me, they unfurled a banner. One of the teachers summoned students from the hall to help hold the banner against a wall so it could be secured there with tape. I lent a hand, still clueless about the proceedings.
The banner proclaimed the school's "English Day" and I was finally told my classroom would be used to proctor the one and only English Day festivity, a multiple-choice test. After the test, the banner was taken down, refolded and stashed until--I presume--the next such observance.
All told, English Day lasted half an hour.