How to tell when you desperately need caffeine

You drag your butt out of bed, and into the kitchen to make some coffee. You turn on the coffee maker, and listen to it gurgle, with joy in your heart because you know your coffee-fix is mere minutes away. When the gurgling stops, you go and grab the pot and your mug, and pour yourself a nice cuppa. You take the first sip, then look at the pot, and realize you forgot to put the coffee in the filter.