There They Go-Go-Go!

Wile E. Coyote attaches a bunch of maces to a string and pole, and unwinds the string when he hears the bird approaching. It's an effective obstacle, and would have stopped the Road Runner except that the pole lifts itself out of the ground and drops on the hiding Coyote before the Road Runner passes. Wile E. is battered and tied up by the end of the fracas.

Example of:
Spike Balls of Doom