Transcript for 'DWTS' Finalists Keep It Light Backstage Amid Finale Pressure
correspondent, cameron mathison behind the scenes for the final rehearsals. Take a look. Reporter: Dancing to the finals can take a toll. We, like, just like lay on the floor for five minutes. I vomited today. Reporter: Aly raisman and zendaya dance a samba tonight, facing jacoby jones jive. They'll compete against kellie pickler's quick step. How is your physical position? I'm still in one piece. Reporter: You feeling well? I have strep throat. I just got some shots this morning. And I'll be fine. Reporter: Zendaya, we learned months ago, is obsessed with ice cream. And one thing that I can do that's pretty cool. Is I can put my teeth in ice cream and I feel nothing. Reporter: You have to prove it. She has strep throat. Reporter: That's great for strep throat. Freezing? Nothing. Reporter: With ice cream cake, this is what derek hough's surprise was supposed to look like. The bad news is I dropped it and I ruined it. It tastes the exact same. Reporter: Mark ballas was surprised his name didn't appear on aly's cake. It's our birthday. Can I write mark? Reporter: And a birthday wish that tonight's performances will be a piece of cake. For "good morning america," I'm
This transcript has been automatically generated and may not be 100% accurate.