Someone

bind pub - !test pub:test

proc pub:test {nick uhost hand chan arg} {
  set arg [split $arg " "]
  if {[set f [lindex $arg 0]]==""} {
    putserv "privmsg $chan :Type !test this"
  } elseif {$f=="this"} {
    putserv "privmsg $chan :Thanks you $nick, for typing \"!test this\""
  }
}