“PORNALITY” comes from PORN + BANALITY, a misheard or misunderstood (if clichéd) expression that takes on a more graphic or sexualized meaning:
HARD-AND-FAST solution becomes “HARDEN-FAST” SOLUTION;
NO-HOLDS-BARRED (wrestling) becomes “NO HOLES BARRED” (stick it anywhere!);
NIP IT IN THE BUD becomes “NIP IT IN THE BUTT";
and, a pornality deliberately scripted for television:
CORNISH GAME HEN became "CORNISH GAY MEN" as mishead by Dick Solomon (John Lithgow) on NBC-TV's "Third Rock from the Sun" (1996-2001).
"Man, you got a buttload of mail."
"Don't you mean 'boatload'? "Buttload" is a pornality."
"I was gonna say 'shitload'."
"Point well taken."