These two sections of flab form the flapagina. Where the lower belly is one wall of the additional vagina and the fupa forms the other wall.
This would be the area of punchline lore "I caught a flap (now flapagina) on the way down to her pussy"
"I was eating her out and she leaned forward and I got caught in her flapagina"
"I was getting ready to stick it in and her flapagina fell on my dick, so I fucked it"