Use the song so sudden to give victim a heart attack!
Rig a contraption so that when the person looks at the key and picks it up, a car will fall on them.
That second one has nearly happened to me.
Feed the keys to them one by one.
Shank their jugular!
Crimple up the poster and shove it down their throat, causing them to choke and die.
Put blades on them, and use them as a nunchuk.
Use the plate to hit the head of the victim.