First used in the movie "Cannibal: the Musical," "Shpadoinkle" was left without a specific definition, it's just a generic exclamation, and makes a great substitution word.
These are from the movie itself:
"Aaaah!Ohhh shpadoinkle!" - exclamation of surprise at being caught in a bear trap.
An undefined word created by Trey Parker while writing the title song for his student film "Cannibal! The Musical" (It was meant to be only temporary until he thought of an appropriate adjective but it ended up sticking). Can be used in replacement of any adjective or in the expletive.