Are you really a d-bag?
"Studies have shown that up to 30% of coffeehouse and restaurant patrons are giant assholes who want to bitch about the supposed fraud regarding the caffeine content of the decaf coffee they made a huge fucking deal about ordering. The D-Bag™ Test strip is a unique new product that quickly and easily determines whether you are the type of jerk to jump up and wave a little piece of paper in your waiter/waitress/barista's face and shriek, 'I knew it! This isn't decaf! Here's the proof!!!' to the irritation of all around you and the embarrassment of anyone unfortunate enough to be accompanying you at the time.
Quick and simple to use, with lab accurate results - simply contact the test strip to the beverage sample and view results. If they corroborate your deep dark suspicions, leap about and shout like the jackass you are. If not, smile knowingly to any human who is unlucky enough to catch your glance, and smugly say, 'It actually is decaf! This time...'"