The pilots and attendants on an airplane must be able to communicate with each other over the intercom without alarming people, so they use jargon that makes no sense to passengers in order to speak in secret.
But thanks to pilot and author of Cockpit Confidential Patrick Smith the jargons out of the jar, and now you'll know what they're talking about when they discuss all-calls, crosschecks and "the equipment":
Definition: According to Smith, all-call is usually part of the door arming/disarming procedure. "This is a request that each flight attendant report via intercom from his or her station — a sort of flight attendant conference call," he wrote.
Doors to arrival and crosscheck