What are all the ways to whack your boss 17 ways

people say there's only 17 but there's really 20.
1. golf club 2, hook 3. wall 4. the container that carries water 5. clock 6. pencil 7. file cabinet 8. fists 9. wheel chair 10. briefcase 11. mug 12 scissors 13 computer monitor 14. keyboard 15. top cabinet 16. ruler 17. letter opener 18. stapler 19. umbrella 20. trash can