As a macro-less alternative, this won't change the value of the cell, but it will change the display of the cell. Right click on the cell in question, then click "Format Cells." In the number tab, click on Custom, then enter the following custom number format
"Joe";"Joe";"Joe";"Joe"
Explanation: Excel number formats have four parts, separated by semicolons. The value of the cell determines which part of the number format is used, and the format looks like this:
[positive];[negative];[zero];[text]
Since each section is a hard-coded string, "Joe" will display no matter what is input, even if a formula is input (unless that formula returns an error). Usually number formats are used to display negative numbers in red, or align values at the decimal, or other cosmetic things. But they can also be used to mess with your friends.
