Be even better if the bag exploded.
Reminds me of a stunt we used to do as kids on Guy Fawkes night... fresh cow patties in a cardboard box, a couple of large bangers in the turd with their fuses conveniently sticking out of the loosely fitted lid. We'd find a doorstep [usually of someone we didn't like] and one would knock on the door while the other placed the box and lit the fuses.
Hehe, we'd run like all buggery and hide close enough by to hear the explosion and the coarse language that usually occurred after getting a shite shower.
Yeah, I know, I was a bugger of a kid, but it would have been a crime not to have carried out the myriad of practical jokes/gags that we spent many hours concocting and planning.