Look at the big black bag. There’s a note on it.
Take the note and read that you have to take out the trash. Take the BAG and use the door to go outside.There’s grafiti on the wall. And dogshit on the pavement. Use the bag on the poop to empty the bag and take the poop. In the trashcan you find a GUN. Use the bag with the gun to load the gun with the crap.
Walk to the right and meet Gary. Use the gun on Gary.
Game source: A copy of the game was found here on the internet.