when an individual is finally able to relieve oneself; the poo feels so good that it is just mean goodness
a poo is never nice, it is just plain mean.
Jessi: Sara, I just had some coffee and am in need of a mean poo...
Sara: Have fun in the bathroom...remember to close the door.
TJ: Dude, I need to go to the bathroom...
Drew: Oh ya? You need to take a dump?
TJ: Not just a dump...a mean poo...