Collecting porn
When I first got Windows 95, I decided I wanted a high value photo of a beautiful naked woman for my wall paper.
Over the years, I've gotten very good at finding sources of free photos. I can now download thousands every day (an unlimited number, really, if I had enough time on my hands).
By far, however, the vast majority are really ugly pictures of ugly people doing ugly things in ugly ways. I try to delete these as quickly as possible so they don't burn my brain too badly.
After all this time, I've kept only about 700 extraordinarily beautiful, erotic pictures (at least to me). I'm still looking for the ultimate beautiful woman, well posed, well photographed, and I never seem to get tired of it.