three-stager
Similar to that of a two-stager, a three-stager is a strenuous part of the human evacuation process which occurs when one engages in the act of wiping excess excrement from the rectum and has to evacuate for not only a second time, but a third, thus leading to the necessary engagement in yet a third separate round of wiping the fecal matter from the anus.
After eating some of Barry's homemade frosted ketchup the other day, I took an unbelievable three-stager which totally smelled like my dad's sweaty grundle.