Someone on another board posted this, looking for its meaning. (Someone said it about her, to someone else.) She assumed it was an insult, but can anyone interpret it more specifically? Presumably it's British. Thanks!
Um, I think it's a reference to fellatio, i.e. the lady in question can "go" for a long time without having to "come up for air." Kind of stupid because barring a headcold or other problem, one's nose is usually quite free.
Or perhaps (in a non-intimate context) it might be a natural extension of the common thought that if you look into one ear of a dimmish person, you can see light on the other side (thus suggesting two holes).

(I wouldn't think of it as specifically BrE, though.)

Students: We have free audio pronunciation exercises.
I thought it meant the same as "air-head".

Teachers: We supply a list of EFL job vacancies

It refers to someone who continually speaks without pausing.

Wow, after 12 years we finally get a reasonable answer. It shows how rare this expression is.