About 10 years I was on the skeleton Xmas/Boxing Day IT day shift - major bank so a few guys and gals had to be there.
Since I was the email guy I had mail queue monitors running while I read a book - with a surprising number of traffic for countrywide empty offices.
Took a closer look and found GIFs and JPEGs flying everywhere with interesting names. Took an even closer look and found traffic was 90%+ doginess being flung around between colleagues over remote dialup. Probably about 50 different people.
"Favourite" - I use the term loosely - was someone doing something deeply unnatural to a stiletto shoe.
Nothing arrestable but alerted my manager. He said there was no policy against it so just ignore it. Obviously not going to tell you which bank doesn't give a toss about their user's use of company equipment for porn-slinging.