In release 12 of Oracle financials we decided to pull the existing Global Intercompany System (GIS) functionality out of the GL product, add a whole bunch of new functionality and make it a product in its own right. We decided to call this new product (wait for it...) Advanced Global Intercompany System (AGIS) - I bet you didn't see that name coming!
Anyway that flash of inspiration for the name was just the start, all Oracle products need a product code of 2 or 3 letters which is used in our source control structure, bug database, object naming standards and all kinds of places. As you may have noticed Oracle has a fair number of products so first choices like INT or GIS were not available and after a long exchange with the people who control these we went for FUN. Now people who have worked with me me over the last few years will already know the puns in this area have been done to death, so I'll spare you those here.
We also have some other features in FUN that like AGIS have impact in many financials areas (e.g. Netting) so we came up with the product name 'Oracle Financials Common Modules' to represent everything under the FUN umbrella. So if you are looking in any Oracle documentation or collateral for AGIS and cannot find it, you might want to search for 'Oracle Financials Common Modules' or look simply seek out FUN