In Wamorama 65, Kymberly Jane is killing time in a doctor's waiting room. She sees a warning about a "defensive smoke alarm system", but disregards it and tries to light up anyway. As you would expect, she gets hit with a pie. Each time she tries it again, the number of pies increases.
I'm going to include a special offer with this clip. There's a special guest star doing an uncredited voice-over as the receptionist. The first customer who can identify the guest voice gets a free clip from any Marshall Stack Productions store:
Due to the distinct lack of customers making a guess, I'll wrap this offer up.
The guest voice is none other than Ariel Andrews, who was gracious enough to record the lines with zero advance notice and send them to me when I was in the middle of editing and realized I had forgotten to get someone for the voice-over.
Love you, too
You'll find the video at 
You have to buy the clip and listen to the voice to answer the question. It's not a random guessing game 
