1. Find a video on youtube with people speaking.
2. Turn off sound.
3. Turn on Audio transcribed captions. (the little CC button near the full screen button)
4. Post funny results here.
You'll have to go to youtube to watch the videos, it doesn't look like captions are available in the embedded version.
This one references Dune, the x-men, and several other interesting subjects:
It's not really new - there are a few videos floating around of people doing this for fun and dubbing them, but there's got to be many more hilarious transcriptions out there.