The third Goosebumps book involving Monster Blood shenanigans.
This time, Evan is babysitting his cousin, Kermit, a junior Mad Scientist who spends all his time mixing interesting chemicals in his basement laboratory. Conan Barber is still causing trouble. Andy tries to get Kermit to help her with her maths homework, but when he intentionally gives her the wrong answers, she comes up with a brilliant idea to get back at him: mix a little Monster Blood into one of his experiments. Shenanigans ensue.
It is one of the nineteen original series books that was not adapted into the 1995 TV series. It was referenced during the Monster Blood event in Goosebumps HorrorTown.
It provides examples of:
- Aesop Amnesia: Even after what happened in the second book, Andy still decides to use the Monster Blood as vengeance against someone who has it in for Evan.
- Attack of the 50-Foot Whatever: For the second time, Evan grows to Paul Bunyan size after eating Monster Blood. At least this time it was an accident.
- Belligerent Sexual Tension: Evan and Andy seem to have a kid version of this.
- Blob Monster: The Monster Blood itself. No organs, not even pseudobods. Just hungry slime.
- The Bully: Conan still bullies Evan in this book, even after Evan had saved him in the second book.
- Chekhov's Gun: Early on, Kermit shows them a special shrinking potion which works. He later uses it shrink Evan.
- Gender-Blender Name: Evan still calls Andy by her real name when she fools him into thinking she slipped some Monster Blood in his lunch.
- Green Is Gross: Monster Blood is described as a green ooze with a Sickly Green Glow.
- Insufferable Genius: Kermit's intelligence is inversely proportional to his social skills.
- Karma Houdini: Kermit never receives any comeuppance or punishment for all the trouble he causes.
- Kids Are Cruel: Kermit is right up there with Tara from The Cuckoo Clock of Doom in terms of being an odious troublemaker. He goes out of his way to get Evan in trouble on purpose multiple times, just for the fun of it, and does the same to Andy.
- Misplaced Retribution: Conan gets his muscle shirt dissipated due to Kermit's experiment. However, Evan is the one who gets beaten up for it instead.
- Parental Neglect: Evan's parents, who tend to treat him like he's more of an unwelcome neighbor than their son, and dump him with his other aunt.
- Puppy Love: Evan and Andy is the most obvious example in the series, with some blatant (adolescent-style) Belligerent Sexual Tension and for the most part behaving like a romantic pairing throughout the series, though never actually becoming an Official Couple.
- Spoiled Brat: Kermit. His mother practically lets him do whatever he wants while always blaming Evan and Andy for his actions.
- Ungrateful Bastard: You'd think Conan would now stop bothering Evan after the latter saved him from Monster Cuddles' voracious wrath in the second book. Think again! Because even in the beginning of the story, Conan shows up to pick on Evan some more. And when Kermit shows up to have his latest scientific experiment backfire on Conan, it just get worse.
