Complex sentence: He wipes into a chair-covering sheet, which is indeed a nasty ghost because two menacing eyes appear and when Pink opens a room, he stumbles upon the chair and throws it downstairs because he thinks that the weird creature is an ordinary chair.
Split into simpler sentences: He wipes into a chair-covering sheet, which is indeed a nasty ghost because two menacing eyes appear and. When Pink opens a room, he stumbles upon the chair and throws it downstairs because he thinks that the weird creature is an ordinary chair.