What are the 16 ways to whack your boss in the game Whack your Boss?

Various versions of the game have either 16, 19, 20, or 24 (official site may have more eventually). There are 19 in the version "Don't Whack Your Boss."

1-16: water cooler, wall, wall hook, his pencil, your hands, chair, cup, briefcase,

scissors, keyboard, monitor, ruler, stapler, wastebasket, top cabinet, umbrella

17-19: wall clock, file drawer, letter opener

20 : Golf club

21-24 : lamp, flower vase, phone, computer tower