you can quite easily set up sounds that are set off by an event in the med, these are the same as the commuication between various characters you hear in the missions, you can create your own set but you have to distribute it with the map.
this will do it
http://dfhq.net/php/utilities/?action=file&id=153
If you heard the laugh that means you already have that sound somewhere in your pff file, whether you donwloaded this ad part of an addon pack like terranova or it's a default im not sure....
Remapping keys to sounds would mean diving into the exe i think..