The scorpion tail thing on GB is basically a large piece of a Goiky bush stick that was used by Fries to pierce her, which worked as the stick was already covered in corruption and it managed to broke through GB's body (which is technically supposed to be really hard to break). The *ahem* "ketchup" actually came from Donut. When she was half-corrupted after being attacked by Fries, the lava (watch BFB 13 for more context) was rising up in her underground factory. Donut was hanging on the stairs, trying to get onto them with GB also clinging onto him. During this, she gets completely corrupted and bites Donut, making him fling her into the lava (despite her being completely unaffected by it) and having some of his filling splatter onto her face.
You hear that kids? She requires a supportive and loyal team member.
