Because it’s zero gravity, the shit would merely float along side the ISS, eventually coating and breaking stuff on the outside.
Time for a space kick practice session. Carefully bag it up and kick it towards the sun. lol
In the old days we used to “honey dip” septic tanks when they got too full of sand to work right. Only one way to fix it, bend a shovel at 90 degrees, add a longer handle and shovel it out using a bucket. Labeled as “honey dipping” back then. lol