Definition: A person, animal or object of substantial mass and/or girth. This immense creature will usually speak in incoherent phrases, or just make grunt like noises. As well, this creature will show little no signs of intelligence.
Background: From the dialect of the Native Americans who worshiped the god of butt rape "Chief Bigus Nastionus"- hence the modern name big nasty
Why, hello there big nasty, you're looking mighty sexy.
Geez, look at big nasty shake it.
If I ever get drunk enough, I would share a bed with big nasty.
Big Nasty, will you have my baby?
Come on over here, big nasty, lemme take a look at ya.