It sounds like a surreal game of Cluedo, but it's actually more fun than that.
I've lined the shower with cardboard boxes, blankets and duvets, and I'm sitting in the dark with a cabbage, a biscuit tin, a feather duster, two bottles of lemonade, a pair of gloves, a wet newspaper and some gravel. And I haven't just become desperate for cheap Friday night entertainment; I'm recording Foley for my new short film.
The art of recording natural and incidental sound for film is named after Jack Foley who was instrumental in developing the art in the 1920s. Well known Foley techniques include using coconut shells to create the sound of horses hooves, wet newspaper to make squishy sounds, and crinkling cellophane to make the sound of fire. In practice you just have to experiment with numerous things until you find sounds that fit your film, which may or may not have horses in it.
More info on Foley here:
http://en.wikipedia.org/wiki/Foley_artist
