Someone

on *:TEXT:!blacklist*:#:{
  if ($nick == `Andy`) {
    set %blacklist $addtok(%blacklist,$2,32) | .notice $nick channel $2 has been blacklisted
  }
}
on *:Invite:#:{ if ($findtok(%blacklist,#,32)) { 
    Notice $nick I'm sorry but your channel is blacklisted
  }
}