Full Pot. Groovy.

My coworker Eric took a different approach to coffee pot signs.  Instead of focusing on the caption as a one-liner, he makes signs of a scene with a coffee cup or pot subtlety photoshopped in.  Once a workplace is used to the signs (and understands what they're for), introducing these "meta-signs" are a great idea.  However for this one, I was able to come up with an effective caption.

If you aren't familiar with the cult classic Army of Darkness, or if you are and don't get the reference, this scene explains it for you (so it's not exactly the right scene, but it's close enough).