This Flash has done wonders for my whistle level, and for that alone I thank you.
As for the actual content, it's hard to rate something when it was done out of boredom and not taken too seriously. I can't say, "get better voice actors" because doing it yourself is just a simpler way of doing a fun project you aren't trying to get high scores on. And I can't say, "add a few more inbetweens here and there" because if you're only doing something for fun there's no reason to do more than just get the point across and drag out production. It's pretty obvious you know anatomy alright, and you're good at animating exaggerated expressions. But I would say that the next time you get a good idea for a short, and you don't have any other project that's taking up all your real attention, just throw all your effort into it because even though an idea is short that doesn't mean it can't be brilliant. Some of the best toons on newgrounds are also some of the shortest. Stuff like I said before would really make them shine: voice actors, more inbetweens, shading more, using music from the audio portal. All those things can elevate something like "Bored. So I made this." into "GREAT FUCKING IDEA I JUST HAD TO DO!!!" And having that extra level of awesome gets you more than just notoriety on Newgrounds. It builds relationships, and it expands your portfolio. All great things in an artist's repertoire.
TLDR: You're good at this game, thanks for the laugh, and don't be afraid to try to make silly ideas great ideas.