During an internship, I spent some time automating reports with VBA. Basically, imagine a few big excel sheets with 1000 formulas and a few thousand lines of VBA.
One of the reports was handed directly to the bosses boss of our boss. After 4 weeks, he came to me and asked why the table entry in row 23 or so was always 84. Well.. I dont know. This data is automatically calculated / retrieved from a database. Went and checked, already sweating, and found that
THE OTHER INTERN COULDNT FIX A FORMULA SO HE OVERRODE IT WITH PLAIN TEXT. WITH A FUCKING PLAIN VALUE OF 84. A FOOKING EXCEL SHEET WITH A THOUSAND DIFFERENT FORMULAS AND LOTS OF VBA. Needless to say, everything is password protected now.