It also made me wonder how delay() would handle a negative number or if it defaults to one or zero.
The argument to delay() is an unsigned long. You need to determine for yourself what -1 as an unsigned long looks like. It will mean a lot more to you if you figure that out that if we tell you.
A hint, though. No, it does not cause delay() to think that you meant 0 or 1, not be a long shot. (Or an unsigned long shot).