a Jaystat is mostly utter crap and is usually made up on the spur of the moment to make the rambling person appear to be incredibly smart, knowledgeable and better than you.
Usually the Jaystater will be called on this type of bullshit but occasionally they will get away with it if the stat is obscure enough. This in turn makes the statistician very smug.
on the other hand the statistician can become rather perturbed and upset if the Jaystat is proven or even assumed to be false. this causes the Jaystater to shake its head in frustration and perhaps slam its fist on the table indignantly or kick a chair.
Always beware of the Jaystat.
"yeah actually reason Goldfish float upside down when dead is that just before they die their system stores extra oxygen in their fins in an attempt to keep it upright. Then all that oxygen gets displaced when the fish dies and causes it to float to the surface of the water."
other person- "nah, really? nah are you kidding? thats weird. i've never heard of that... wait.. is that a Jaystat?!"