I was told the following story by someone who used to work in a military recruiting office, in the days when they still existed on the high street, and were manned by serving military personnel - and they assured me it was true!
It was a tri service office, with an Army desk, Navy desk and RAF desk. The entrance to the recruiting office from the high street was via a sort of air lock, two sets of see through glass swing doors. But one set opened one way, and the next set the opposite - so one was pull, the next push, or vice versa. Anyway, it became apparent that, in the vast majority of cases, the way the applicant entered the office was indicative of which service they wanted to join...
If the applicant passed seamlessly through the two sets of doors they invariably went to the Navy desk. If they struggled a bit but got through quite quickly they went to the RAF desk. If they were still struggling after a while the Army recruiter went and got them and took them to the Army desk.....
Well, as I've already said, my friend did say this was a true story...