Highjack, sounds like high jack. Is there a story?

highjack, sounds like high jack.
Is there a story? just my curiosity.

The origin of the word highjack (informal for hijack) seems to be obscure. A few dictionaries shed some light, though:

There are two folk etymologies:

That it arose from someone wanting a lift on a truck calling “Hi, Jack” (the exclamation plus the name), until this was used often as a trick by robbers.

That it comes from seamen who were robbed by prostitutes in former centuries in London. Prostitutes would call out “Hi, Jack” to passing sailors. Instead of receiving the services they expected, some sailors were instead robbed by an accomplice. (Wikipedia)

Probably back-formation from highjacker, perhaps from jacker, holdup man, from jack, to jacklight. (The Free Dictionary)