Jess can hear that Jack has taken the mic to announce her entrance and is putting on his best showman's voice, "And coming up now is my adorable little sister. It took a lot of training to get her ready for this task. I was worried we'd have to replace her with something more trainable like a monkey or a dog."
As she enters, Jack's self satisfied smirk, which appears whenever he makes a fool of her, transitions into a look of confusion. His face then turns bright red as some of the lucky bride's extended family glare at him. Since they've never met her, his digs intended to embarrass his twin in a fake playful manner now look to them like cruel jabs at a little girl.
Meanwhile his groomsmen seem to put the situation together and as expected can't wait to throw him under the bus.
His best man takes the mic, "I think you're being a bit hard on little Jessie buddy. She's doing a very good job. Right guys?"
The rest of them quickly affirm while Jack struggles to regain his composure. He's still working on that when Jess reaches him.
She puts on her best tearful expression, "Me sowwy me no good as doggy. Me love you big bwotha."
As soon as she finishes mom takes her arm and drags her back to her seat and whispers to her, "I don't know how you pulled off this stunt, but I hope it was worth it."
As Jess looks around to see how venomous those good intentioned relatives looks have become and hears Jack's friends laughing at his emberassment, she decides for whatever earful she's going to get later this moment was worth it. Who knows, maybe Jack will finally learn to stop acting as old as she looks.