Testicles
From XKCD Wiki
Testicles are a form of redhead.
[edit] Where Found
In the trash. White trash, to be exact.
[edit] Cautions
Contain at least nine types of STDs, and a piece of Nash lodged inside.
[edit]
A duck's quack does echo, contradictory to popular belief. The perpetrators of this myth are being very masturbatory.