In the 16th through the 18th century there was a great deal of unsactioned raiding and pirating going on in the seas of the newly discovered Americas, the perpetrators of these acts were called Privateers.
Here in the 20th and 21st century there has been a large increase in the amount of
homo-eroticism in the world at large, leading to many new
slang terms for the
anus which is commonly associated with homosexual sex. One such term is Bung.
So logically a Bungaleer is one who engages in privateering of the
anus.. or more commonly Ass Piracy