Really, the only thing you should flush down the toilet is toilet paper. Toilet paper is made to break down in water and therefore, rarely causes a blockage.
Other paper products such as facial tissue, paper towels, napkins, and baby wipes should not be flushed because they do not break down. While they may go down out of sight they could be building up in the pipes and can end up causing a toilet blockage.
Other things I have found and don't recommend putting down the toilet:
- tooth brushes
- hair clips
- small perfume bottles
- hair brush
- ID cards (especially if you don't want to be identified)
- potatoes (yes, I found a whole potato)
And the list goes on...