Seemingly frivolous litigation is a tongue-in-cheek hallmark of the American legal system. About two decades ago, a then-79 year old grandmother brought a suit against McDonalds when she burned her legs after spilling coffee on them, ushering in a chorus of critics of the legal system (even if, as explained in the bonus fact, the complaint wasn’t so far off base). And of course, crazy lawsuits aren’t only American. For example, in 2004, a driver in Spain struck and killed a 17 year old boy on a bicycle and then sued the boy’s parents for the damage done by the bike to his car.

But sometimes, the complaint levied isn’t so strange — rather, the defense is.

In the fall of 2008, an Illinois man named Ronald Ball claimed that he opened a can of Mountain Dew, took a gulp, and found a surprise inside — a dead mouse. While disgusting, such an incident is not unheard of. There have been allegations of a chicken head included in a box of wings at McDonalds, an animal toe discovered in pre-packaged hummus, a human finger in a roast beef sandwich at Arby’s, a dog tooth in a New York Chinese restaurant, and certainly dozens of others. Some are real, some are hoaxes, and determining which is which may prove to be a fool’s errand. In Ball’s case, he swore it was true, and filed suit seeking in excess of $300,000.

But Pepsi was determined to prove that Ball’s claim was one of the hoaxes. As recounted by the Madison County Record, which covers the legal system of Madison, Illinois, Ball claims that he took a sip of his allegedly tainted Mountain Dew, drank a bit, and immediately got sick. He then poured the remaining product into a Styrofoam cup and out came the soda and the dead mouse noted above. He called the toll-free phone number on the side of the can to levy his complaint, and an investigator got back to him, requesting that Ball send the soda and the mouse to the company so they could investigate. He obliged.

Pepsi came to court with pretty sound — and rather vile — evidence: the science behind what would happen if a mouse was sealed inside a can of Mountain Dew for days if not weeks at a time. Ball, by his own admission, claimed that he sent a nearly-full mouse to Pepsi — which, of course, is why he was so disturbed. Pepsi claimed that the can was bottled a few months before Ball opened it, which neither side seemed to dispute. For the coup de grace, Pepsi then argued that had a mouse somehow gotten into a can of Mountain Dew in August, it would not have been much of a mouse in November. Pepsi’s expert, a veterinarian, asserted that the acid in the soda would have melted away any recognizable features of the mouse: “after 30 days in the fluid, the mouse [would] have been transformed into a ‘jelly-like’ substance.'”

As of this writing, the case is still pending.

Bonus fact : The McDonalds’ coffee lawsuit? It wasn’t so frivolous after all. As mental_floss explained, at the time, Mickey D’s served coffee “at temperatures ranging from 180 to 190 degrees Fahrenheit” while at-home coffee only reaches temperatures of about 140 degrees by comparison. The full mental_floss article goes into great detail, but the major takeaway is that “skin can burn quickly when contacted by liquids” at temperatures in the 180+ degree range — which is probably why McDonalds received a few dozen burn complaints every year prior to the lawsuit.

From the Archives: Why Diet Coke Loves Mentos: The science behind the experiment. (Or, do cool stuff with soda without turning a mouse into a jelly-like substance.)

Related: For some reason, this four pack of 2 liter bottles of Mountain Dew costs almost $100.