More sophisticated than just shouting from a car, but not as refined as shouting git your fuckin' rat out.
Designed to disorientate and bewilder the recipient.
Guy washing his car in front of his son: "Shhhh-mookles I found another dent!"
Son: "What does shmookles mean?"
Guy washing his car in front of his son: "Look it up on Urban Dictionary, Sport."