A few recalcitrant souls will fight with me about it. "But a business has no incentive to honor the mug!" they'll cry.
"It's not about incentives," I'll reply. "The mug entitles the bearer to free refills. That's what makes it such a great idea."
"But then they should get the money from the idea!"
"No way. It was my idea."
"But the idea doesn't make any sense!"
Ah. Now that's an argument that merits a bit more discussion.