There are several outlets you could try: punching bag, vigorous exercise (going on a hard run usually helps calm me down), writing (or if you're mad enough, scribbling) your feelings on paper and then tearing it up.

Throwing rocks is something I do but it's only an option if you have a place to do it: go outside to a place where no one's around and there's a lot of space. Pick up a rock and imagine a negative feelings flowing out of you and into the rock. Then chuck it as far as you can. Repeat it with more rocks until your arm is too numb to throw anymore or you feel calmer. I actually feel sad at this point sometimes and can sit down and have a good cry which also helps.