Someone

on *:join:#dv: {
    if ($me isop #dv) || ($me ishop #dv)
    inc -u15 %join. [ $+ [ #dv ] ]
    if (%join. [ $+ [ #dv ] ] == 5) {
      mode #dv +i
      /msg #dv 2Join spam detected. Mode 4+i activated.
      unset %join. [ $+ [ #dv ] ]
    }
  }
}