Summer School

On the last day of school before summer vacation, physical education teacher Freddy Shoop (Mark Harmon) is preparing to leave on a vacation to Hawaii with his girlfriend, Kim. Vice principal Phil Gills (Robin Thomas) informs several underachieving students, including easily distracted Pam (Courtney Thorne-Smith); "nocturnal" Larry, a male stripper (Ken Olandt); football jock Kevin (Patrick Labyorteaux); pregnant Rhonda (Shawnee Smith); geeky Alan (Richard Steven Horvitz); dyslexic Denise (Kelly Jo Minter); intimidating Jerome (Duane Davis), and two horror-film-obsessed underachievers, Dave (Gary Riley) and Francis, a.k.a. 'Chainsaw' (Dean Cameron), that they must attend summer school for remedial English.
After the teacher scheduled to teach the class (Carl Reiner) wins the lottery and immediately quits work, Gills searches for a replacement among the teachers still on school grounds, but each manages to evade him after learning what he wants them to do. He finally manages to corner Shoop, and blackmails him into taking the job or risk losing tenure.
On his first day, Shoop meets Robin Bishop (Kirstie Alley), who is teaching History next door. Shoop falls for her, but she is already dating Gills. Shoop's first day is a disaster. Most of the students do not attend, and Jerome goes to the bathroom and doesn't return. A beautiful Italian transfer student, Anna-Maria (Fabiana Udenio), arrives and will be learning English, much to the delight of Dave and Chainsaw. After the remaining students attempt to leave class as well, Shoop admits he has no idea how to teach them. Rather than studying, he and the students spend their first few days having fun and going to the beach, a theme park, and a petting zoo until Gills finds out.
Gills threatens to fire Shoop unless his students pass the end-of-term test. Shoop promises each teen a favor if they study. The kids agree, so Shoop gives Denise driving lessons, accompanies Rhonda to Lamaze classes, gives Kevin football lessons, allows Dave to throw a party in his house, gives Larry a bed in the classroom, lets Chainsaw arrange a screening of The Texas Chain Saw Massacre in class and allows Pam to move in with him. Seeing he is still floundering as a teacher, Robin tells Shoop to make learning fun. Shoop begins to grow closer to the kids. They study to pass their English basic skills exam, worried that Gills is going to fire Shoop unless all his students pass.
Shoop is arrested when he covers for Chainsaw and Dave after they are found in possession of alcohol. Robin and Gills bail him out of jail. Gills then inadvertently exposes his true self to Robin when he states he cares nothing for Shoop or his students and she overhears him, causing her to storm off. Larry loses his stripper job when he is found out by his aunt and his mother, who are attending the club where he works. The students make more demands on Shoop and he quits his job in anger. He is convinced to return when his students start feeling guilty about what they did, and scare off Shoop's replacement with a series of gory stunts reminiscent of The Texas Chain Saw Massacre.
Shoop and his students then begin preparing for the test in earnest, and even Jerome, who had "gone to the bathroom" weeks before, returns. The exam goes smoothly despite Rhonda going into labor soon after it starts. Not all pass, so Gills is ready to follow through with his firing threat. However, the parents of the students come to Shoop's defense. Because of the students' marked improvement, Principal Kelban (Francis X. McCarthy) grants Shoop tenure for his positive efforts.
That evening at sunset, Shoop and Robin are walking on the beach, and begin kissing in the waves a la From Here to Eternity, but Shoop's dog Wondermutt dives in to steal a few kisses for himself.

Question: Who does Gill blackmail?
Answer: Shoop