Someone

on *:text:!greets on:#:{ if ($nick isop $chan) || ($nick ishop $chan) { set %greet [ $+ [ $chan ] ] on | .notice $chan Greets are now enabled. }
  on *:text:!greets off:#:{ if ($nick isop $chan) || ($nick ishop $chan) { unset %greet [ $+ [ $chan ] ] | .notice $chan Greets are now disabled. }
    on *:text:!greet*:#:{
      if ($1 == !greets) { halt }
      if (%greet [ $+ [ $chan ] ] == on) {
        set %greetz [ $+ [ $address($nick,2) ] ] $2-
        notice $nick Your greet for $address($nick,2) has been set to $2- $+ .
        halt
      }
      if (!$2) {
        notice $nick You must specify a greet $nick $+ !
      }
      on *:join:#:{
        if (%greet [ $+ [ $chan ] ] == on) {
          msg $chan [ $nick ] %greetz [ $+ [ $address($nick,2) ] ]
          else {
            notice $nick Get a greet! !greet GREET
          }
        }
      }
    }