The IDFWU mug by Jawbreaking lets those around you know that you "ain't f*ckin" with them. At least, not before you've had your morning cup of Joe.
Mornings are a difficult time for many. The closest thing we have to make waking up in the AM a pleasant experience is caffeine, the miracle drug.
The absolute worst thing that can happen in the morning is when someone attempts to interact with you as though you are a fully functional human being before you've finished your first cup of the good stuff. I think Big Sean put it best when he sang, "I got a million trillion things I'd rather f*ckin' do/Than to be f*ckin' with you." Amen.