1. The fullest and complete way to express how amazingly low (yet still present) the effort going into any sort of task is.
2. Expression of the 'best, worst, best' of something.
Dave: "I tried thought about making you a cake for your birthday, but it was looking to be too hard. So I traced this picture out of the cook-book for you.. with crayons. Happy Birthday or whatever,"
Mitch: "...thanks Dave, that is the most Terrifantastibad effort anyones every made for me!"
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Matt: "Terrifantastibad Dragon Fanart is now a meme."