-The fucking White Noise! Argh my skull! It's like ear rape!
-The screech Feral Ghouls make when they are looking for you
-The sound of a Deathclaw approaching me at night
-The "out-of-ammo" sound
All of them have to do with Fallout 3. Hrmm.
Oh and when people scratch that plastic with the lines on it, usually used for folders and placemats...