I use these "cleaning bills" to place on my students' desk. We have a token system in class with fuzzies. If you don't use fuzzies, there is a page with a blank for you to write the price.
If the students walk into class the next day and see this on their desk, they know that it was not clean and I had to clean it for them. Then they know that I took 2 fuzzies out of their cup! Works wonders for students that don't care about cleaning up after themselves.