I wonder if "a good way to corrupt a file" sounds like an idiomatic
expression to others. (an expression that makes no sense by the wording).
Anyway while use of a floppy drive is very unreliable, I'd hardly say that
you are necessarily going to corrupt your data, I think you are more likely
to lose your changes.
I don't know that you are going to get just one kind of message, or whether
that message would be indicative of a particular failure.
One way that Excel files are frequently destroyed is to open an Excel file
in MS Word and to save it. I don't know if that is the most frequent
cause but Excel itself seems to sufficient for most people. Purposely
misusing a hex editor would be one way to destroy any file.
I have a page on Backing up and recoverying data, nothing there on
methods useful to destroy a file (at least I hope not).
http://www.mvps.org/dmcritchie/excel/backup.htm