Related Clues:

• Best seller
• Best-seller
• Top-selling product
• It doesn't stay on shelves
• Huge seller
• Product that's hard to keep in stock
• It's in high demand
• Powdermilk Biscuits, per Keillor's faux jingle
• It flies off store shelves
• Top-seller
• Top seller
• Tickle Me Elmo, in 1996