A, sometimes big, but flat and disgustingly sagging ass. Normally while fat black women just plain have big, round asses, most overweight white women tend to have pancake asses. Sick.

The act of extreme masturbation. You must "knock one out" whilst in close proximity to any of the following; Your mum, a nun, your boss, a member of parliament, George Michael. A person with capabilities to act upon catching you mid self-abuse obvisouly ups the ante. Ejaculation must be reached before your danger wank target comes (no pun intended) to investigate. The higher the chances of being discovered with one's pants down, pulling one's war face is obviously where the danger comes from. The more danger involved the harder (or softer) it is to complete the task in hand (snigger). The more dangerous the better. The chance of being arrested, pummeled by an angry father or having your hand severed by an arab's sabre means that you are a pro "Danger wanker."

a girl with a flat sagging ass

when a girl has a flat/saggy ass

Does not apply to just women, many men have flat ass too. Have you seen the amount of them who have their belts under their ass? Insufficient buttocks to hold them up.

The flatest booty out this bitch

Well, you see, the fat that protruds from the well-known pancake meat was designed by geneticist Dr. Roberto Sally. Sally was a very white man with a very unmanly last name. Try as he might to woo women with some toosh, all he could get were the flat bottoms of gay men..and Sally the geneticist was no experimenter. Through a series of slightly tragic, yet still amusing events, his non-governmental experiment to change his last name failed, producing a mutant virus that caused anybody who ate pancake meat to become living pancake asses.
Thankfully, I Am Legend Two was not needed to be filmed because only the isolated Mormans of Utah were used for testing, and with their new pancake asses they were only inspired to become even more fruitful and started shitting pomegranate everywhere. Eventually, due to the high amount of salt in their drinking water down by Salt Lake city and such an incredible amount of diarrhea going on, the population died out and the Catholics, again, rejoiced.
Meanwhile, Dr. Roberto Sally continues his quest to get laid.