It's when you don't feel fat except when trying to squeeze by somewhere or usually someone. Narrow walkways are conducive to Big Butt Paranoia as well as trying to get out of a car back seat in a two-door. Being in a crowd can cause this as well.
I felt fit and trim, but after squeezing by everyone at the crowded deli, I developped a case of Big Butt Paranoia.
Everytime I get out of that car, I get big butt paranoia.
I always get BBP in that elevator.
It's usually people with small butts who get big butt paranoia.
A bald man who's big ass hits e-stops and doesn't know it. Also a bald man who is uncircumcised and also called a aardvark for short. Walks on his tippy toes and swings his arms like a baboon.
Look there goes big butt bob ass hitting e-stops, walking like a baboon with a uncircumcised dick.