A mode of eating popularized by Eric Cartman highlighted by jamming food into the rectum and deficating out of the mouth instead of vice versa. Eric won a $20 bet with his Jew-friend Kyle for proving that introretrogestion is humanly feasible.
Popcorn is one food that would be difficult to eat using introretrogestion.
The act of inserting foodstuffs into the anal cavity, as means of eating.
Did you know Randy practices introretrogestion now? I saw him get a whole turkey in there!