Very funny. You nearly did me in with the platforming on that last level, but the boss was surprisingly easy.
For such a short time, you really did an awesome job. Graphics are good, controls are pretty tight, and the sound is amazing. I pretty much ignored the music, but the voices are incredible. I'm happy the game wasn't any longer than it was, particularly after the last two levels, as the joke would have worn thin.
The humor very immature, but it worked for me. As funny as the kitty cannon is, I found the profanity laser to be one of the funniest thing's I've seen on Newgrounds. I almost think that the language in the rest of the game should be clean, because that would make the profanity laser that much funnier. Imagine if the protagonist walked around saying, "Darn it! Out of my way, silly! Fiddlesticks, that hurt!" Then you start firing swears all over the screen.
Advice. Hmm... there were some small control issues. Wall climbing was easy, but I think the mechanic for the actual triangle jump wasn't great, making certain areas very hard to get through. I didn't notice anything else, even though I wish I could complain about the rage factor of the last two levels. I also wish I could complain about sado-masochistic the game is, but anyone without a sense of humor shouldn't play anyway.
Oh, the flamethrower... dreadful weapon. More often than not, I found that it's terrible range and trajectory was more likely to get the player killed than to help. The shotgun had that problem occasionally, but outside of a few isolated areas, it worked okay.
You said that you worked your ass off, and it shows. Congrats.