A glitch exists where if the player gets caught and they try to transform back, there is a small chance they will lose their greegree; however, this glitch is not common. If the player has a full inventory, and teleports from Ape Atoll without removing their greegree, they will lose it.
After Monkey Madness II, it can be reobtained from Zooknock in the Tree Gnome Stronghold, north-west of the Gnome Ball Field, if lost by selecting the 'Large Ninja' greegree, as it is not listed as Kruk monkey greegree. No materials are required. If it is lost during the quest, you can get it back talking with Zooknock at the end of the Ape Atoll Dungeon.