Tank!

[Imperialistic]

It's when you post right after another. Here is the rule:

Originally Posted by Forum Rules

c) The act of posting two messages to the same thread in quick succession - with no other members posting in between - is known as 'double-posting'. Often, users neglect to mention something in their first post and then make another in order to include it. This is not allowed. If you wish to add something to your previous message, simply use the edit feature to modify the original post. Currently we permit double-posting if each post is in reply to a different message. Users are encouraged to combine their posts into one.