Despite claims this phrase originated on "The Simpsons", it actually existed long before it was used in the show. The phrase is intended to portray the distortion of facts when passed from person to person.
Its use in "The Simpsons" was accurate; Bart starts a rumour by whispering to one person who whispers it to another, etc. By the time the rumour reaches the front of the crowd, the phrase "Purple monkey dishwasher" has been added to the end due to people mishearing the original rumour as it passed from person to person.
Due to the popularity of "The Simpsons", the phrase has since become a commonly used response to opinions stated based on hearsay and unconfirmed rumours.
Person A - "I heard from a friend of a friend that John cheated on Linda with Karen!"
A person who collects used condoms and cleans them out by effectively sucking the semen from the insides.
Mikey: Don't talk to Tommy, that guy's a Boston Dishwasher.
Franky: What's that?
Mikey: He sucks cum out of condoms like cocaine residue from a Ziploc bag
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the USCoast Guard in the area of Southern Florida.
"Base we've got some square groupers floating outside of Miami harbor."
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.
I had a trucker's tan after driving for 10 straight hours on a sunny day.