Mine

on $*:TEXT:/^[!@.](check|whoischeck) */si:#: {
  if ($nick isop $chan) || ($nick ishop $chan) {
    if ($2 == On) {
      set %checker [ $+ [ $chan ] ] On
      /notice $nick 1The whois on join checker is now turned. On
    }
    elseif ($2 == Off) {
      /notice $nick 1The whois checker is now turned. Off
      unset %checker [ $+ [ $chan ] ]
    }
    else {
      /notice $nick 1You may not use this command.
    }
  }
}
on *:JOIN:#: { 
  if ( %checker [ $+ [ $chan ] ] == On ) {
    set %chan $chan
    enable #GroupRaw 
    set %whoisnick $nick
    /whois $nick
  } 
}
#GroupRaw off
raw 319:*:{ 
  if (!%chan) { halt } 
  else { 
    msg %chan 1 %whoisnick is currently on $+ :4 $remove($3-,%,@,+) 
    disable #GroupRaw 
    unset %whoisnick 
    unset %nick
  } 
} 
#GroupRaw end