Do you mean that on the same event e.g. Object A collides with Object B, a random sound will be played?
If so, one way to do this is to give your sounds a set of indexed filenames like sfx_0, sfx_1, sfx_2.
Then on your trigger event use the audio action "play (by name)"; in the audio file name field write: "sfx_"&choose(0,1,2)
You could of course use choose with non-indexed file names e.g. choose("bang","laser","grenade"), but indexing gives you more flexibility, especially if you have a lot of sounds to pick between - you may even want to switch from using choose() to floor(random(min,max)) as this would allow you even more control over what was played.
For bonus variation add the "Set playback rate" action directly underneath this action, setting the playback rate to a random number.