Most people drink coffee for the caffeine, whether to help them wake up or stay alert, but some people drink it because they like the taste and don’t want to get the crazy jitters associated with the drink. For these people, who don’t want to be fooled into drinking the go juice, there are the D+caf strips.
These strips allow you to tell whether or not some dork at a coffee shop gave you caffeine, when you actually ordered decaf. Just dip the strip in and it will change colors if it detects more than 20mg of caffeine. And because you detected it, you are still calm enough not to throw it at the dude.