There's a rather bizarre oddity that can occur with Reverse Bottle Adventure.
When you empty the contents of a bottle under normal circumstances, the game code will start with a check to see if there is a full bottle of milk (item value 26) in the proper inventory slot. Then, if it finds a full bottle, a half-full bottle of milk (item value 31) will be put on both the button pressed and the inventory slot, regardless of the old bottle's contents.
This leads to an interesting side effect. If the memory address we're trying to use RBA to manipulate stores a value of 26, we can change it to a value of 31 (the same as a half-bottle) by emptying the contents of the B bottle, without needing Bottle Adventure to get a full bottle of milk on B.
Half-milk RBA is useless for editing the main inventory, since you can only put a full bottle on the normal bottle slots. You can endlessly perform Half-Milk RBA with item amounts, but you can also just as well use normal RBA to get infinite item amounts.
For example, if you have a fish on B, a bottle with a normal poe on C-Right, and exactly 26 bombchus, dropping the B fish will give you 31 bombs. However, once you drop the fish, you should immediately swap c-right to a different item (an empty bottle, bugs, or fish will work nicely), so to recapture the fish on the B bottle without setting the ammo count too low.
| Item Amounts | |
| item on c-right | item amount updated |
| Fairy | Deku Stick amount |
| Fish | Deku Nut amount |
| Lonlon Milk (full) | Bomb amount |
| Bottled Letter | Arrow amount |
| Big Poe | Deku Seed amount |
| Poe | Bombchu amount |
| Spooky Mask | Magic Beans amount † |
† - Can be done by getting Full Milk on B, drinking it while the Spooky Mask is on C-Right, then using up 5 Magic Bean, but is pretty useless.
| Halfmilk RBAs | ||
| c-right | start items | end items |
| Goron Mask | Have the Goron Tunic, Kokiri Boots, but not the Kokiri Tunic, Zora Tunic, Iron Boots, or Hover Boots. | You will obtain the Kokiri Tunic, and Zora Tunic, and keep the Goron Tunic, and Kokiri Boots. |
| Zora Mask | Have the Master Sword, Broken Sword Icon and the Deku shield, but not the Kokiri Sword, Biggoron Sword, Hylian shield, or Mirror shield. | Get the Kokiri Sword, Biggoron Sword, keep the Master Sword, Broken Sword Icon, Deku shield, and lose Hylian shield, Mirror shield. |