Short for I'm - fixing to - going to - want to.
Extremely stupid adulteration of the original slang, finna.
Very prevalent in certain dormitories of The University of Minnesota. Carlson douchebags specifically have not heard of this word.
Man I'm hungry, immafinnagonnawanna go to Chipotle.
God, I miss her. Immafinnagonnawanna visit my girlfriend in St. Cloud tomorrow.