"There was this quiet, old janitor that worked our office building who was scheduled to retire on Christmas, so our Christmas party kind of included his farewell; we gave gifts to each other, put up a Christmas tree, people brought cakes and pastries, Christmas stuff.

"Then here comes the old janitor and he leaves a fairly big bag of presents under the tree; we're all kind of surprised because no one seemed to interact with him that much, but nonetheless we thank him and wish him the best and stuff, then he leaves and presumably sets off to the Midwest. The next day, we open the presents, including his.

"Turns out, the retiring janitor gave everyone in the office a little bottle of sulfuric acid. Everybody got one, even me, I still have it. We don't know where he got them or how much they cost, but apparently he hated our guts.

"Our new janitor has no idea why everyone is treating him so nicely."

—Anonymous Business Insider reader