To take over an internet forum and replace the original intent of the group. Usually a myspace group infested with trolls who systematically spam and flame original members of the group causing them to leave and or become butthurt.
The word "castroed" comes from the rebellious revolutionarry leader Fidel Castro who overthrew the Cuban government.
Ha! your group just got castroed!
being locked up, not free or not given permission to go out anywhere.
"Im sorry I cant go, my wife castroed me to stay at home"
"that girls huge boobs always be castroed in that shirt. she needs to take it off"