The sound a turd makes when it hits the water. Usually followed by the splash back of water into the anus.
Naval officer 1 : "I think North Korea just tested another long range ballistic missile!"
Naval officer 2 : "Nah that was just Freddy dropping a kadoonka off the port bow."
Sound effect created by the elongation of Pinnochio's nose. Usually used by non-puppets (humans) as a vocal effect accompanied by a hand gesture, with the fingers pointing towards the face, which is demonstrative of a growing nose.
NB The number of gesture repetitions and/or length of the kaboop and gesture should be relative to the extent of the Billy bullshit ie. How far it is off the scale.
"Hey bru, have you seen Michael Ball lately?"
"He was just on his way to the bar to buy the first round."
"Kaboop!" (accompanied by gesture)