Dreadful,
Right away I could tell this Flash was going to have some problems. The art was really sloppy, and when it didn't look terrible, it looked like it was hastily traced from the game. Even then, it still looked messy. The animation was incredibly choppy, and nothing flowed well at all.
The sound was also very poor. The gun sounds were really loud compared to the inaudible speech. The only voices I could hear were shrill and sounded like someone trying to sound kind of like Cartman from South Park. Then there were overused fart sounds. I don't even know why there were fart sounds, since half the time nothing was on screen to warrant them.
I found no humor in this Flash, aside from a chuckle as a bunch of poorly drawn bad guys were killed in really limited animation. Even then, I think I was laughing for a reason other than the one intended. The jokes were mostly fart and poop jokes, which are really the lowest form of comedy. Then there was a gatling gun with a dick for a barrel, and it really bothered me that you didn't use that for a better joke. If he was using it to shoot the fat guy instead of a standard gatling gun, that could be funny. Even then, the animation on the gatling gun was just you moving the symbol around.
To improve this, I would really step up your sense of humor, then work on getting animation to flow. There was no smoothness to the animation and it all looked so horribly choppy. Next, work on sound issues. Get a better microphone or record at a louder volume. If you do these things, you might be able to make a decent Flash. This, however, is garbage, and best forgotten.