There is a bug in Text To Speech which makes the person speaking sound like a helicopter! Hilarious trick when done correctly.
Ok, this is what you do:
1. boot up Windows XP
2. Click on Control Panel
3. Click on the Speech icon
4. Click on the Text To Speech tab
5. Select Microsoft Sam from the drop-down menu
6. In the text bar, type this WITH the spaces:
My roflcopter goes soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi soi
7. Click on the Preview button
8. As soon as it says "soi", start slowly speeding up the speech
9. Laugh your head off
NOTE: You can add "soi" as many times as you like, but remember to place a space between each one or this trick does NOT work