I don't really keep it "secret" anymore, but I did get caught a long while back when I was something like 14. It was worse because it was on my bro's PC (he had a loving huge screen it was awesome). He did not like the joke too much, he should've been hiding his research a little bit better anyways, like maybe not in his Pictures folder in a folder titled "Nothing" and the thumbnail revealing hot busty chicks.
Also the screensaver would take some of his pics out from time to time, at the worse times too like during that Christmas party. It didn't help that his room was also the TV room.
After that I used some safer methods, like a secure drive and a couple other tricks. You had to look very loving hard to find any of my dealings.