Summarize the following:
To look angry instead of sad, you should engage your upper lip a little. Stick the bottom lip out just as you would for a sad pout, but then stick the upper lip out a bit too. Just like with the sad pout, you can stick your lips out further if you want to exaggerate the expression. If you want to sell the angry look, consider wrinkling your nose, rolling your eyes, or squinting at the person you are talking to. Look straight ahead and do not drop your head like you would if you were trying to look sad. To look downright furious, try knotting your brows and flaring out your nostrils. Crossing your arms very tightly against your body and having a rigid posture will help get the message across that your pout is an angry one. If you are talking, make sure you sell your emotion with your voice as well by talking loudly, repeating the same phrases, and laughing sarcastically. You can also try stomping your feet, closing doors loudly, and making other loud noises to make yourself sound more intimidating. An angry pout should still be somewhat playful, even if you are genuinely annoyed. Avoid screaming and insulting other people. Throwing a temper tantrum will only make you look like a bully.

Summary:
Purse your lips. Use the rest of your face. Use off-putting body language. Use an angry voice. Don't be too aggressive.