This is a shaking coffin, as requested(I think) in the Make it really scary contest.
Step 1: The Rocking Mechanism
This is the shaking mechanism. The long stem in the middle , the hydraulic pump, provides the up and down movement for the shaking. The slanted cylinders on the sides are things to move the pump in different directions. The card looking things at the ends of the slanted cylinders are carts for people to pull and push to create the rocking effect.
Step 2: The Coffin
This is the coffin which can open up to let a person inside. The persons friends could move the carts to make the person inside enjoy the ride of their life.
And that is how it works. Thanks for watching!