It is totally an interesting trick to frustate someone.U can send a user lots of messages in his inbox.For this you have to......
1. Download the java version of nimbuzz.If you dont have java version simply go to the software area in this site.
2. Select the user you want to flood whose inbox and then select send message.
3. Simply write down a message and then click on send message for as many times you want.
4. Do it rapidly.As much as you will click the message will go to him for so many times.
Perhaps you have enjoyed this post.If you have any idea send it to my mail address: arif.afghanboy@gmail.com. If it seems acceptable i will post your ideas in this site....Thank you.