Early 70s baby here, i never saw Fast times since it was rated R, and i was only 8 or 9 when it came out.. same with Porkys, which i remember desperately wanting to see.. i think Revenge of the Nerds might have been R rated too(?) Not that i *never* snuck peeks at R rated flicks, just for some reason i never saw the ones i really wanted to see the most.
All i can say is thank the good lawd that PG13 became a thing right around the time i hit that age, otherwise there are a slew of other films i woulda missed.