A trash can that in addition to being a trash can will spawn an extra janitorial NPC to help clean up lots. It will spawn up to one of each that you have in your game. If you have all EPs (or Complete Collection) there's eight total. One is spawned by the Maxis lot controller so you can have up to seven. It will take a little to generate the NPC, since it makes sure not to create duplicates. It will also skip over any you don't have the pack for, in case you still refuse to install SuperStar or something.