This has been explained to me as a gunt or ponch, some would call it a fupa (frontal upper pussy area) the bulge of top of box flab we all know and love. I am imagining the nifkin would be the femal flaps and the dome would well...be the dome of flesh warding off potential pennetrators.
"Yo! Did you hear what happened to Harry?"
"Yeah I heard he was bottom feedin that fat bitch Lola and was suffocated by her nifkindome!"