Dirty Dancing

In the summer of 1963, 17 year-old Frances "Baby" Houseman (Jennifer Grey) is vacationing with her affluent family at Kellerman's,[10][11] a resort in the Catskill Mountains. Baby is the younger of two daughters, and plans to attend Mount Holyoke College to study economics in underdeveloped countries and then enter the Peace Corps. Her father, Jake (Jerry Orbach), is the doctor and friend of Max Kellerman (Jack Weston), the resort proprietor. Baby is befriended by Max's grandson Neil (Lonny Price). Baby develops a crush on the resort's dance instructor, Johnny Castle (Patrick Swayze). Johnny is the leader of the resort's working-class entertainment staff. Baby encounters Johnny's cousin Billy on a walk through the resort grounds, and helps him carry watermelons to the staff quarters. The staff hold secret after-hours parties in their quarters, and Baby is surprised by the "dirty dancing" they engage in.[12] Intrigued, Baby receives a brief, impromptu dance lesson from Johnny.
After Baby discovers that Johnny's dance partner, Penny Johnson (Cynthia Rhodes), is pregnant by Robbie Gould (Max Cantor), a womanizing waiter who is also dating and cheating on Baby's older sister, Lisa (Jane Brucker) and several other female guests, she borrows money from her father to pay for an illegal abortion for Penny. Jake agrees to give the money to Baby even though she says she can't tell him what it's for. Penny eventually accepts the money, but says there is another issue. Johnny and Penny perform a weekly dance at the Sheldrake, another nearby resort. Penny will miss her performance if she goes for the abortion, and they will forfeit their salary for the season. Billy suggests that Baby fill in for her. Johnny scoffs at this, which overcomes Baby's initial resistance. Billy and Penny insist that Johnny can teach anyone to dance. Johnny begins to teach Baby the Mambo, and the two spend several awkward practice sessions together. Baby gradually begins to improve, and a romantic attraction grows between them.
Billy takes Penny to a traveling doctor for the abortion while Baby and Johnny perform at the Sheldrake Hotel. Their performance is mostly successful, although Baby is too nervous to accomplish the dance's climactic lift. Johnny and Baby return to Kellerman's and find Penny in agony. Billy explains that the "doctor" turned out to be a back-alley hack who caused severe damage to Penny. Baby brings her father to help Penny, but when Johnny takes responsibility for Penny, Jake mistakenly assumes Johnny is the father. Jake treats Penny, but is angry that Baby used his money to pay for the procedure, and forbids Baby to associate with Johnny or his friends. Baby goes to Johnny to apologize for her father's behavior. They dance, and afterwards have sex. Jake tells his family they'll be leaving early over breakfast. Lisa protests, because she wants to sing at the end-of-season talent show. Jake gives in, and Baby continues to see Johnny despite her father's warning. She pulls Johnny off the footpath when her father is nearby, and Johnny is hurt that she won't stand up for him to her father. Robbie sees them during their argument and makes a derisive remark about "going slumming" with the staff. Johnny assaults him.




An iconic scene from the dancing finale[13][14]
Due to his growing feelings for Baby, Johnny refused payment for sex with another Kellerman's guest, "bungalow bunny" Vivian Pressman. Vivian instead pays Robbie for sex in his cabin, which is accidentally interrupted by Lisa. When Vivian leaves the cabin the next morning, she discovers Baby leaving Johnny's cabin after. Later in the morning over breakfast, Max and Neil Kellerman reveal to the Housemans that Moe Pressman's wallet was stolen while he was playing a card game with other guests. Vivian accuses Johnny of the theft in a fit of her jealousy over Johnny's rejection. Johnny is unable to provide a verifiable alibi, in order to protect his relationship with Baby. To save Johnny from being fired, Baby confesses that Johnny did not commit the theft because she was with him in his cabin that night. Johnny is cleared of the theft after it is revealed that two elderly guests, Mr. and Mrs. Schumacher, stole Moe's wallet along with wallets of other guests. Max fires Johnny anyway for having a fraternizing affair with Baby. Baby and Johnny embrace and bid farewell to each other, saying they'll never regret their affair, despite her father's objections.
Baby and her parents watch the end-of-season talent show. Jake bids farewell to Robbie, and gives him a recommendation letter for medical school. Robbie thanks Jake, willingly reveals that he got Penny pregnant and insults her and Baby, which leads Jake to yank the letter back. Staff and guests (including Lisa) of Kellerman's are singing the closing song together when the door opens and Johnny walks in. He's returned to do the last dance of the season. Johnny leads Baby onstage, interrupting the show which is already in progress. He makes a brief speech about how "Frances" has made him a better man. Baby and Johnny dance a more provocative version of their Mambo duet, and the other "dirty dancers" join in. Baby runs to Johnny and executes the elusive lift move they'd practiced. The dirty dancers pull guests from their seats to join in the celebration. Jake apologizes to Johnny for thinking he got Penny pregnant, and reconciles with Baby. The film ends with the entire cast dancing joyously to "(I've Had) The Time of My Life".

Question: Who discovers that Johnny's dance partner, Penny is pregnant?
Answer: Baby