The Stanley Tumbler, this year’s smash hit, is, at first glance, a win for the planet. It’s durable. It’s reusable. Unlike the throwaway plastic bottles it’s meant to replace, it doesn’t generate mountains of plastic trash.

But the craze has sparked some less-than-sustainable behaviour. People boast about owning dozens of them. When Target released special editions, including a much-coveted Starbucks version, it caused a mini stampede.