“PORNALITY” comes from PORN + BANALITY, a misheard or misunderstood (if clichéd) expression that takes on a more graphic or sexualized meaning:

Examples --

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).