Tickety-boo is a British expression originally meaning all set, ducks in a row, put to rights, and it derives from the propriety and sense of order acheived by being properly ticketed (for example as a passenger, or a shipper) when confronted with the appropriate authorities (for example, a conductor or Customs inspector). Tickets are also used to control the flow of parts in repair shops, for example, and in governing the administration of meals in some contexts (hence, "meal-ticket" and "pawn-ticket"). The construction is just a baby-talk formation, a kind of silly slangery also found in constructions like "peek-a-boo", "nighty-night-night" and "hickory-dickory-dock". Like "bibbety-bobbity-boo" it has no inherent meaning except a sense of playful innocence.

Gob, meaning mouth, is as old as the hills, and the sense of being gob-smacked is a reasonable extension akin to being knocked in the jaw.

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