No such thing as a free lunch

While that may be true, there is in fact such a thing as free coffee. At least, today there is. Provided you bring in your own tumbler, Starbucks will fill it with brewed coffee at zero charge.

Now this is the part where people will find a way to deride what is A) An eco-friendly initiative and B) Free damn coffee because it's Starbucks. I can hear it now: "They just want to save money by not using paper cups. And besides, it's shameless pimping for their own tumblers". 

Fine. Even if we grant that Starbucks, the big evil corporate monolith that it is, hasn't any moral fiber, it's still free coffee. Free. Coffee. The why of it needn't be benevolent. That, in this case, it is, only serves to make an already sweet deal even tastier.