Like I said, in Out of Space you need to clean your space house, and the cleaning process involves lots of garbage disposal. You need to get rid of bags, aliens, and spare furniture and the Grinder is the prime place for that.

If you are stuck on the Grinder, cranking its a manual lever to make the surprisingly low tech machine works, it's not uncommon for a roommate to pass by and throw some extra trash on the top of the trash you are already destroying, and if you have multiple teammates you can end up cranking that lever for a while as people keep putting extra stuff on the Grinder. After a while, you don't even care about what they are putting there and you could easily destroy something important without notice.

Fun Fact - If the alien knocks someone down, they put him in a cocoon and the Grinder is the normal way to get free them so putting people in the grinder is indeed a mechanic in the game.