Re: @AC "wouldn't be common freakin' sense to not surf dodgy websites at work?"
No, Nick, we had real pornographic computer images in the late 1970s. Not very good images, mind, but they existed. It was crude technology, but it worked. How crude? Look up CROMEMCO's Cyclops and Dazzler (1975). Things rapidly improved from there (how could they not?), and by the mid 1980s .tga made it's appearance ... As did SGI. And trust me, as soon as bit-mapped displays showed up, there was porn on them. It would seem to be human nature.
The Great Renaming (1987) was arguably brought about partially because of the binaries that were being posted at random all over USENET. As a guy who ran a news farm back then, I can assure you that most of said binaries had been porn since roughly late 1982.
Data heavy? Does SLAC count? How about Bigger Blue? We could see a spike in traffic when someone was eyeballing porn, even in the old days. Maybe especially in the old days, when practically every byte of connectivity had to be accounted for.