Kakugo no Susume, Battle Royal High School Recommendations
Both have a school setting with the main protagonist fighting against various strange opponents. Battle Royal High School is set in a non-post-apocalyptic world while Apocalypse Zero is set in a post-apocalyptic world. Both are action-packed anime filled with violence, gore, and nudity. They both have a lot of random scenes that make you go WTF at different times. If you like one, you will like the other as well.