There’s no brand that’s as strongly associated with free samples as Costco. People have been known to tour the sample tables at Costco stores for a free lunch, acquired piecemeal. There are even personal-finance and food bloggers who’ve encouraged the practice. Costco knows that sampling, if done right, can convince people that its stores are fun places to be. (Penn Jillette, of the magic act Penn & Teller, has on more than one occasion taken a woman on a date at a Costco warehouse.)

“When we compare it to other in-store mediums … in-store product demonstration has the highest [sales] lift,” says Giovanni DeMeo of the product-demonstration company Interactions, a department of which handles Costco’s samples. That department is Club Demonstration Services, and it—not Costco—staffs the sample tables.

While DeMeo insists that the short-term spike in sales isn’t the only effect of product sampling that matters—it’s great for making customers loyal to stores and brands over longer periods of time—the figures are impressive. In the past year, Interactions’ beer samples at many national retailers on average boosted sales by 71 percent, and its samples of frozen pizza increased sales by 600 percent. (These figures are in line with the few others that are publicly available.)