In college I lived in a house with 3 three friends. One of them had found somewhere a box of hardcore porn mags. He, and I think he had help, cut out a whole bunch of pictures and snuck them in all sorts of places in my room. It included coat pockets, shirt pockets, in shoes, hidden everywhere for me to find. I don't know how long it was that I kept finding these, but luckily never at a too embarassing moment.
Speaking of finding porn magazines, how about we start a campaign of sending ALL old porn magazines anyone finds anywhere to the Clinton library... all at once. Let's call it "Monica Day".
Back in my youth I worked in a mailroom of a large law firm. The Supply Room manager had a huge collection of porn mags (mostly penthouse). He was a disgusting little man that we all called Gollum (he looked very much like Gollum in the old animated LOTR movie).
When he was at luch, the entire mailroom staff broke into the supply room, grabbed all of his mags and took them back to the mailroom. We all then proceeded to color bikinis and one piece bathing suits on all of the pictures with magic markers. We then returned the mags to the supply room....
Another dorm prank. Switch the CDs into the wrong cases. Just make sure you switch 3 CDs at a time. Then the prankee cant easily just switch the CDs into the other jewel case. TOTAL PAIN THE ASS!