High Mallampati Score and Obstructive Sleep Apnea

I have been reading several articles on scalloped tongue and obstructive sleep apnea (correlation). Many of these articles bring up a Mallapati Score, Class I-IV, Class IV being the most severe. I do not recall ever being asked to do this "Stick your tongue out" test. Has anybody here had a Mallapati test?

Please let me know.