I switch mine a lot too and have found that the best way for me is to press down on the sim with a finger and simultaneously slide the sim out. Like already said, it works best with a clean dry finger to get good traction.
I googled it and the laugh was also used in the Zorro tv show.
I assume it originated from The Legend of Sleep Hollow and made its way into other shows and, later, advertising (someone on the Youtube video of Sleep Hollow mentions hearing the laugh in ads.)
Just an FYI but theaters across the nation on Sunday are having a ONE SCREENING ONLY of Ice Age 3D for Father's Day. Check your local theater for time since it varies. I checked the two theaters near me and one is having its screening at 2pm and the other at 3:30pm.
Ok that makes sense, don't know why I didn't even think of that :p
Here's another question though, why did Bob try to kill Selma? Bart didn't like her in the first place, it would have made more sense to try and kill Marge or Homer, wouldn't it have?