The largest number we have a name for is the googolplex, or 10 raised to the 10^100 power. In the 1930s, people had a less precise approach to unfathomable quantities—they used bazillion to exaggerate large and indefinite numbers of things. (fun fact, googolplex is how Google gets it’s name)
If you’ve worked in the food service industry or been to an American diner, you’ve likely used the phrase eighty-six in reference to something left off a menu. In the ’30s, eighty-six referred to a sold-out food item at a restaurant. Over time, the phrase became more frequently used as a verb meaning “to refuse service” or “to throw out.” The exact etymology is unclear, as Merriam-Webster notes, but there are plenty of theories about where the term actually came from.
According to the OED, when cockamamie was first coined in 1931, it was a children’s slang term that referred to decal applied to skin, like a temporary tattoo. By 1936, it had come to be used as an adjective to describe “a ridiculous, crazy, or wildly eccentric person.”
According to a 1935 issue of Popular Science Weekly, the phrase flying by the seat-of-the-pants could have actual avian origins. “Blind flying,” they explained, “was known as ‘seat-of-the-pants’ flying, for fog-bound pilots without instruments soon learned to tell whether they were flying right-side-up by the pressure against their parachute packs.” According to the OED, the phrase has two meanings: When used in reference to a person, it means “tending to act instinctively, spontaneously, or expediently”; when used in reference to an activity, it means “done on the basis of practical experience rather than technical knowledge; informal; inexact.” To fly by the seat-of-the-pants and make spontaneous plans could lead to a ripsnort of a time. Or it could be a complete boondoggle. Who’s to say?
Another slang term 1930s people have in common with Gen-Z, sus, according to the OED, is an abbreviation of suspicion or suspect, and indicates a feeling that questionable activities are afoot. While today’s youth tend to use the word as an adjective (“you’ve been acting pretty sus, sus was used as a noun in the ’30s and often preceded by on. If one was on sus, they were suspected of committing a crime or some other nefarious act.
Someone’s impressive, unexpected floss could leave you gobsmacked, British slang for “flabbergasted, astounded; speechless or incoherent with amazement,” per the OED. Coined in 1935 as the compound of gob (“mouth”) and smack (in this context meaning either “to slap” or “to make a noise when separating your lips”), gobsmacked combines the two meanings to evoke imagery of slapping one’s hand over their mouth in shock, or dropping one’s jaw in surprise.