log_sanitizer.rb

class MySanitizedLogger
  def initialize(logger)
    @logger = logger
  end

  def <<(message)
    @logger << message.gsub(/password=[^&? "']+/,'password=REDACTED')
  end
end  
RestClient.log = MySanitizedLogger.new(Logger.new(STDOUT))
RestClient.get "http://api.nokaut.pl/loguj?password=ala"
# RestClient.get "http://api.nokaut.pl/loguj?password=REDACTED", "Accept"=>"*/*; q=0.5, application/xml", "Accept-Encoding"=>"gzip, deflate"
# # => 200 OK | text/xml 126 bytes