Patrols make sound effects to a video with the sound turned off
A tv&dvd player or computer or tablet (possibly per patrol)
A video of a short action sequence
As many items that can be used for sounds as possible, such as:
pots and pans
Give some examples of how sound effects for radio, plays, TV and film are made - from coconut shells hoof sounds to punching pillows instead of people.
Then give each patrol a short action filled video clip to make sound effects for and some time to prepare their show.
For maximum effect screen the patrol making the sound effects off from the rest of the audience, and let them reveal their secrets at the end.
Great example here:
For older groups you could have them actually record the sounds and experiment with changing them with a processor on a computer, then use them.