Well, the easiest way would be to kill Thunderbugs, for Thunderbug Juice. They appear in the tower stage, or in many High Ranked (6 or more stars) quests. But, if you don't have access to those quests, then there is another way. You can trade battlefield jewels (obtained by mining in the volcano) to the jungle veggie elder. There is a 33% chance when you give it to him, that you will get your Thunderbug Juice. Otherwise, i think you will get a brute bone, or a giant bone. So, once you get your battlefield jewels, just start doing gathering quests to the jungle and bring one jewel with you. Then, trade it to him. If you get your juice, then keep it and save. If you don't get it... exit out and reload your file and try again. Kind of a long process, but I hope it helps. -Kirby Solid