Nine to Five

Judy Bernly (Jane Fonda) is forced to find work after her husband, Dick (Lawrence Pressman), runs off with his secretary. Judy finds employment as a secretary at Consolidated Companies. The senior office supervisor, Violet Newstead (Lily Tomlin), introduces Judy to the company and staff, including mail room clerk Eddie, alcoholic Margaret Foster, the opportunistic boss Franklin Hart, Jr. (Dabney Coleman), and Roz Keith (Elizabeth Wilson), Hart's executive assistant. Violet reveals to Judy that Hart is supposedly involved with his buxom secretary, Doralee Rhodes (Dolly Parton). Hart exploits and mistreats his female subordinates, with backstabbing and sexist remarks. He takes credit for Violet's ideas, cruelly yells at and threatens Judy on her first day after an equipment malfunction and sexually harasses Doralee, spreading rumors about an affair that never happened.
When Violet discovers that a promotion she was hoping to receive was instead given to a man because of sexist hiring practices, she confronts Hart about it, as well as the rumors about Doralee (who enters Hart's office just in time to hear, and now realizes why she has become unpopular with the other secretaries). Violet storms off, stating that she needs a drink. Doralee takes Hart to task over his transgressions, informing him that she keeps a gun in her purse and will "turn him from a rooster to a hen with one shot" if his sexist behavior continues. She then also leaves, stating that she needs a drink.
Judy, upset over the firing of Maria, a dedicated employee (due to an infraction overheard by Roz, who had been eavesdropping in the ladies' room), joins Violet and Doralee in storming out of the office, and the three women drown their sorrows at the local bar before retiring to Doralee's house to smoke a joint given to Violet by her teenage son. While there, the beginning of their friendship forms, and they share fantasies of getting revenge on Mr. Hart: Judy wants to hunt him down like an animal in a classic mobster scenario, Doralee wants to rope him like a steer in a Western scenario, and Violet wants to poison him in a twisted Snow White-style scenario.
The following day, a mix-up leads Violet to accidentally spike Hart's coffee with rat poison. However, before he can drink the tainted coffee, Hart falls out of his desk chair and hits his head on the credenza desk, which knocks him out cold. On hearing he has been rushed to the hospital, Violet, thinking he is sick from the accidental poisoning, rushes to the hospital with Judy and Doralee in tow. At the hospital, Hart, who has regained consciousness, leaves on his own without being seen, and the three mistake a dead police witness for their boss, steal the dead body (to prevent an autopsy), stash it in the trunk, and drive off. Soon they discover they've stolen the wrong body, so they smuggle it back into the hospital.
Hart turns up alive the next morning, much to the shock of Violet, Doralee, and Judy. During a break in the ladies' room, the three speculate on what could have happened, but ultimately decide to consider themselves lucky and simply forget the whole matter. However, Roz, hiding in one of the stalls, overhears them and relates the conversation to Hart. He confronts Doralee about the hospital incident and demands that she spend the night at his house, or he'll have all three of them prosecuted for attempted murder.
The three kidnap him and bring him to his Tudor-style mansion, keeping him prisoner in his bedroom while they find a way to blackmail him. The three women discover an embezzlement scheme, and must keep Hart tied up at home while they collect evidence on it.
The women use Hart's absence to effect numerous changes around the office, in his name: flexible hours, equal pay, a job-sharing program, and a daycare center. Hart is so hated around the office that nobody questions his absence, with the exception of Roz, whom Violet sends away for a multi-week training.
Meanwhile, as Judy is guarding Mr. Hart, her husband Dick comes to ask her to come back to him. She refuses, forcefully throwing him out. Hart's adoring wife Missy (Marian Mercer) returns from vacation early, putting the women's plan in jeopardy. Hart manages to break free and return the stolen items back to the warehouse. Then he escorts the women to the office at gunpoint. Hart is appalled by the changes which have been made in his absence, but receives an unexpected visit from Russell Tinsworthy (Sterling Hayden), the Chairman of the Board, who has come to congratulate Hart for increases in productivity - but he wants the equal pay eliminated. Margaret Foster is no longer an alcoholic thanks to the company's alcohol rehab program and Maria is now back with the company on a part-time basis and sharing her workload with another employee. Tinsworthy is so impressed that he recruits Hart to work at Consolidated's Brazilian operation for the next few years. Roz returns from her training and is stunned to discover Violet, Judy, and Doralee celebrating in Hart's office.
In the epilogue, it is revealed that Violet gets promoted to Hart's job, in which Roz must now answer to her; Judy falls in love and marries a Xerox representative; Doralee quits Consolidated and becomes a Country and Western singer; and Hart is abducted by Amazons in the Brazilian jungle and is never heard from again.

Question: What does Hart hit his head on?
Answer: Credenza desk.