@ The_Almighty_Duelist if you cant find $iif in the help by typing /help $iif then maybe you should update ur mIRC =/

here is just another way to do it. well just 1 of many ways...

on *:TEXT:!commandhere:#: {
  if (%on.off) { code here }
  else { msg # Pissoff }
}
on $@*:TEXT:/^(!on|!off)$/S:#: {
  if ($nick isop $chan) { 
    $iif($regml(1) == !on,set %on.off on,unset %on.off)
    msg # Script is now $iif(%on.off,on.,off.)
  }
}

or like this with flood control

on $@*:TEXT:/^(!on|!off)$/S:#: {
  if ($nick isop $chan && !$($+(%,onoff,.,flood),2)) { 
    set -u3 $+(%,onoff,.,flood) on
    $iif($regml(1) == !on,set,unset) %on.off on
    msg # Script is now $iif(%on.off,on.,off.)
  }
}