If Willy Smith, in fitting attire, enters the portals of Madame Astorbilt’s house or grounds, to which he has not been invited, in order to mingle with her party guests, he has “crashed the gate” to do so.
Or if little red-haired Sammy Jones finds a way to sneak past a ticket-taker at the Polo Grounds or Madison Square Garden, he too “crashes the gate.”
Neither one has literally crashed anything, other than social or legal convention, but such an entrance, uninvited or non-paid, has been popular American designation since, approximately, the end of World War I.
No one knows and there is no clue to the person who became the first gate-crasher.
