Everyone gets voiced except Andy.

Code:
On @!*:Join:#mychannel: {
  if ($nick != Andy) {
    mode $chan +v $nick
  }
}


Andy gets voiced.
Code:
On @!*:Join:#mychannel: {
  if ($nick == Andy) {
    mode $chan +v $nick
  }
}


And when they join a channel, they'll be devoiced anyway.