A variation on the term "Moose knuckle," but referring to the bulge in the crotch of a hugely obese woman.
"Look at the Brontosaurus Knuckle on her!"
"I saw Rosie O'Donnell on the cover of People. Tight sweatpants and total Brontosaurus Knuckle evident."
"She went from Camel toe to Moose knuckle to Brontosaurus knuckle in 6 short months."