The logistics of "knickers round the neck" are very challenging. Surely only a small pilot's head and neck and a very large girl friend would, as it were, meet the requirements.
It has to be a leg-hole/waist contortion surely.
[PS I have just had a sneaky rehearsal without wife being aware. Even the leg-hole is difficult. Perhaps I have big ears].
Is the matter an aviation urban legend?
Give the problem a try!