could keep it simple

menu nicklist {
  -
  .Turn Mimic $iif($group(#mim) = on,Off,On):{
    $+(.,$iif($group(#mim) = on,dis,en),able) #mim
    $+($iif($group(#mim) = off,un),set) %mim $$1
    echo -a Mimic is now $group(#mim) $iif(%mim,an is set to annoy $v1)
  }
  -
}
#mim off
on *:text:*:#:$mimic($nick,$1-)
on *:action:*:#:$mimic($nick,$1-)
on *:nick:if ($nick = %mim) set %mim $newnick
alias -l mimic if ($1 = %mim) return $iif($event = text,msg,describe) # >> $2-
#mim end