My sister keeps soda cans and styrofoam cups on her bedroom floor.
When my sister (24) is done with a soda can or Styrofoam/plastic cup, she will put it on her bedroom floor. She has been doing this for months and now she has hundreds of cans and cups covering her floor. She has places she can step and that's it.
I went into her room one day, saw her floor and asked why. She panicked and said it was for a project, which is not true. She will not let anyone in her room, ever. The picture I included was taken in September.