1. The amazing feeling one gets after taking a massive poo which makes the person feel great.
1. I had the most pooptastic feeling last night.
An amalgam of the word "Poop" and "Fantastic." Something that is so fantastically "poopy" that it is noteworthy. This particular quality invokes feeling not of dismay, but awe. When something is pooptastic, it is unalterable - you must simply walk away.
This software application is utterly pooptastic, I can do nothing with it.