When I was a young girl in the middle of a older brother and younger sister, my mom created the toy monster to help control the mess around the house. She would give us warnings to pick up our stuff. If we didn't pick it up, she would come around as the toy monster and put all the toys that weren't put away into a bin. We wouldn't see those toys for a week.
In an attempt to control the messes around the house, I brought the toy monster to our house. I have changed things up quite a bit. I first mentioned it to Gavin when I warned him several times to pick up his toys. I told him the toy monster would come if he didn't pick things up. I explained that the toy monster comes around and takes toys we leave out. He took it very seriously. He asked me several questions, like "What does he look like?" and "Where does he live?" I wasn't quite sure how to handle these new questions. I didn't want him to be scared. I told him that the monster lived in the closet in the living room. He went and looked in the closet immediately. Great. I came up with the idea that I would go into the closet and come back out as the toy monster. They loved it. So, now every evening, I set a timer. The boys have that amount of time to pick up before the toy monster appears. The alarm goes off and the boys go crazy. I go into the closet and come back out as the toy monster. I go from room to room as a monster. They do a really great job picking up, so the monster only eats a few things. Eli even gives it a few toys because he loves to see it eat the toy.
It has been a fun game for the boys and and has really motivated them to clean up when I ask. I usually help and work on my own messes. We have had a pretty clean home as a result. We'll see how long it lasts.