The Hanford nuclear reservation in Washington state produced most of the plutonium our nation used from the the beginning of the atomic bomb through the 1980s. As one can imagine, this production also led to massive amounts of toxic waste. However, one of its sources is not part of the usual suspects.
The area is the focus of the largest environmental cleanup operation in the country right now, and that includes scrubbing all the rabbit feces because it is radioactive. The jackrabbits have taken quite a liking to the nuclear sludge, which contains a radioactive salt that they can't get enough of. According to the Seattle Post-Intelligencer,
Jackrabbits routinely burrowed into those sites. They found the salt, liked it, and licked it. Later, they pooped it, leaving slightly radioactive scat all over the ground.
Check out Rachel Maddow's segment below for more information on this operation, and the radioactive rabbits.