Fast forward to the wedding day. Baptista and Katherine are ticked off because Petruchio is very late. Both worry about looking like a couple of idiots if he blows them off. Kate runs from the room in tears and Baptista says something like, "She's just mad because she's a shrew."
Biondello enters and says that Petruchio is on his way over. He then describes Petruchio's little procession to Baptista's house: Petruchio is dressed in some crazy costume and looks like a bum. He's also riding in on a lame old horse that appears to be ready for the glue factory.
Petruchio enters looking exactly as Biondello described and pretends that he didn't just roll up to his wedding looking like a Technicolor hobo. Baptista is shocked and asks him to change clothes, but Petruchio blows him off and says Kate isn't getting married to his clothes.
Then Petruchio jokes with Baptista about how he's going to have sex with his daughter that night and says he's going to find Kate right now so he can get a little preview.
Meanwhile, Tranio and Lucentio scheme about how to seal the deal with Baptista. They need to find an old man to pretend to be Lucentio's dad so Baptista will sign the dowry contracts. (Remember, Baptista recently agreed to let "Lucentio" marry Bianca. They can't ask Lucentio's real dad for help because Tranio is parading around as Lucentio.)
Lucentio says he and Bianca just want to elope, but they can't because Hortensio is always watching. Apparently, Lucentio's "tutoring" lessons have paid off and Bianca is just as into him as he is into her.)
Gremio enters and says he's just come from the church, where he watched Kate and Petruchio's wedding. (This is another event that occurs off-stage, so we depend on Gremio's narration for the details.)
Gremio says that Petruchio acted like a jerk – he swore at and then back-handed the priest during the ceremony and then stuck his tongue down Kate's throat when the ceremony ended. The make-out session was just a tad noisy. Petruchio also pounded all the wine instead of sharing it with his guests.
The wedding party enters just then and Petruchio announces that he and Kate have to run, but the guests should go ahead and party at the wedding reception without them. Baptista and Kate beg Petruchio to stay, he refuses, and Kate says that's fine but she's not going anywhere.
Grumio tells us in an "aside" that Petruchio's taming plan is about to begin. (An "aside" is a way for a character to say something for or to the audience without the other characters hearing.)
Petruchio repeats that everyone should enjoy the party, or get lost – he really doesn't care either way. Kate is going home with him because she's his wife and therefore his property, along with his house, his barn, his horse, his ox, etc.
He warns the guests not to touch his bride, and pretends that he and Grumio are being attacked by thieves as he draws his sword and runs off with Kate.
The wedding guests laugh at this big production and joke that crazy old Kate has married someone just as crazy as she is.
Baptista shrugs his shoulders – Kate's no longer his problem – and tells Bianca and Tranio (as Lucentio) to sit at the bride and groom's. They'll just pretend all that unpleasantness didn't happen and will try to enjoy the celebration without them.