Difference between 'nod out' and 'nod off'

[Dasha]

Test No. incompl/inter-8 "Going on foot", question 6

When a film is really boring in the cinema, I tend to nod ..........

(a) out
(b) off
(c) to
(d) through

Test No. incompl/inter-8 "Going on foot", answer 6

When a film is really boring in the cinema, I tend to nod off.

Correct answer: (b) off

Your answer was: incorrect
When a film is really boring in the cinema, I tend to nod out.
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What the difference between the
_ to nod out _ and to nod off
THANK YOU VERY MUCH

Dasha

[Alan]

This means to fall asleep. I have never heard of nod out.
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English as a Second Language
You can read my ESL story Saying It Twice

[Adu]

[Clara]