CSB - One time around 99-00' I was in the middle seat between a woman at the window and dude on the aisle. This was pre-ipod/iphone so I had all of my music loaded on my work laptop. After takeoff I pulled my laptop out and cranked it on the tray table, then was fishing around in my laptop bag for my earbuds not paying attention to the screen. What I didn't realize was that unbeknownst to me, my work buddies had hijacked my laptop and changed my bios so that upon boot up, my wallpaper was changed to a jpeg called "The Beard": a rather heinous snapshot of a woman spread eagle with a vast, Amazonian bush stretching from mid-thigh to navel.
That image sat on my screen in full view of my row mates for a full 20-30 seconds until I finally found my earbuds in the bag that was down between my feet and I looked up to realize what was going on. The lady next to me was looking out the window so I'm not sure she saw it but I know the dude on the aisle did. He didn't say shit and I flew the whole way from LAX to AUS with a closed laptop wondering if airport security was going to meet me at the gate.