That was really great for the most part. I think you nailed the voices perfectly, and it was really funny (that part with the horse was the funniest thing I've seen in a while... totally out of left field!).
The dong joke DID outstay its welcome (there usually some joke or other in your flashes that stays too long) but in general the flash was very well-paced.
The graphics were a bit simple, but they were effective. If you want to improve them, you could add a bit of shading perhaps.