Remember that crazy plot to kill and castrate Justin Bieber? Now there's some creepy audio to go along with it.

As you may recall, the diabolical plans of the perpetrators - prison inmate Dana Martin and his accomplices Mark Staake and Tanner Ruane - were discovered before the weirdos could use hedge clippers to turn the Biebs into a eunuch.

In the audio, Martin can be heard explaining to Ruane how to strangle Bieber using Martin's signature paisley scarf to mark the murder as his and “seal the deal.”

(Signs that you're not working with the smartest assassins in the world: You have to explain how to suffocate someone.)

There's also mention of purchasing said hedge clippers and going after the “pitbull,” which is Bieber's code name for reasons we don't understand.

"Did he go over the Bieber thing with you?" Martin can be heard asking Ruane, who responded, “Nah. The way I like to work dude, I like to know as little as possible. He's gonna use one of the things you gave him, and then he's gonna take care of it."

The police believe “take care of it” here refers to Bieber's planned demise. Ruane later requests $5,000 to “get” the job done, another wily, thinly-veiled code word that was captured during the call.

So what you had here were the world's dumbest criminals hatching a murder plot on prison phones they knew were monitored. Yo, Mensa -- meet your newest members.