The sound made by an IED (improvised explosive device) as it detonates, the ska being the initiator and the DOOSH being the main charge. Also the name of the game played by route clearance Combat Engineers by saying skaDOOSH whenever they expect to be blown up.
"Dude that culvert we're about to drive over looks sketchy."
"Oh naw, man, it's probably fi-skaDOOSH!"
"I just peed a little."