A painfully large bowel movement that, in its aftermath, brings a sense of euphoria and slight weight loss.
Roommate 1: "Where have you been the past 2 hours?"
Roommate 2: "Ah, sorry bro, I was taking a magnifishit."
When someone has doen something really moronic and foolish. Can also be used to describe something thats cheap, nonfunctional, and/or a waste.
Those hicks that live in the trailer park have a truck thats real magnifishit.