Gob-mouthed- to gape- has been in print since the 19th c. I wonder if gobsmacked is a variant?
Memory plays tricks, but I am "sure" that I heard it in the U. S. Army in the 1940s.
Gob-stick is in the OED as a spoon, but to an American musician, it is a clarinet.
Many words from gob = mouth. Gob string is a bridle.

Another possibility: God-smacked =euphemized to gobsmacked, struck dumb.
Tickety-boo, I think, was spread in America by Dnny Kaye (see Nigel Parsons, above).
It is the name of a champion Dalmatian, Kat: Ch Tickety Boo