I don't find a whole lot of humor in the posters "funny ads" series myself

I think the point (unconsciously made) of this particular one has to do with the absolute rights a monopoly, such as Starbucks, has. this kind of freedom (which ironically really enslaves both oppressor and oppressed in the final analysis)... to say whatever the fuck and people will continue to give them their money... this is the six bucks for something that costs two cents to make side of it, And the fact that masses of people, children even, are worked to death from dawn to dusk in virtual slavery and receive a very small percentage of the two cents that it costs Starbucks to produce said cup of shitty tasting coffee.