We have all been there. You are in love with a person and you would move heaven and earth in order to make them happy and then they dump you. Your first reaction is probably going to be sadness. You will cry for a bit and think that you will never find anyone to love you. After that sadness fades, you will likely find that you are angry. This anger can lead you to do some strange things, like seek dumped revenge. While it is normal to feel this way, it is best just to let it go and not act on those feelings. However, if the ex was a truly horrible person and has ruined a lot of things for you, then there are somewhat innocent little ways in which you can get back at them for what they have done.
One way to seek dumped revenge is to mess with your ex. You can do this in a lot of ways. You can get a disposable cell phone and call them at all hours of the night, not letting them sleep. You can also enter their email address in several spam websites so they get all kinds of spam emails.
Just do not do anything that would make things bad on someone else, such as ordering a lot of pizzas and having them delivered to their house. First of all, you will be putting the pizza place out of a lot of money because your ex is not going to pay for it. So do not do anything childish like that.
If your ex was cheating on you or had created an online dating profile before they broke up with you, another way to seek dumped revenge is to create your own profile as someone else and pretend to be interested in them and then stand the ex up once a date is made to meet. Only do this once though and do not say mean and hateful things to your ex when she replies asking why you did not show up. Simply ignore her after that.
Seeking dumped revenge is well and good within certain limits, but you really should evaluate why the relationship ended. If it ended because you tend to fly off the handle and get made and then seek revenge on a person, then your ex was right to dump you. Also, you need to keep in mind that acting immaturely and getting revenge on them is not going to make them want you back. It will only serve to reinforce their reasons for dumping you in the first place.