I was only tangentially related to the group that first affixed a piece of cheese to the wall and dubbed it Cheezus. I was friends with one of the main members of that circle, and thus it was through her that I was told the story. It's a blurry sort of memory now, so I don't know the wheres and whyfors at this point and will the bulk of it up to adolescent humor. During lunch, someone didn't want a piece of cheese and put it on the wall. It stuck there, and thus was wildly entertaining.
When the cheese remained on the wall for weeks, it became a holy object to the group as the custodians didn't bother to remove it. I don't believe I ever found myself in the presence of Cheezus, but it remained on the wall in some obscure part of my high school for the rest of that year if I do remember correctly. It might have been there for longer than that.
People really do see Jesus in interesting places, don't they?