In like Flynn an idiom that came into use in the twentieth century. We will examine the meaning of the idiom in like Flynn, where it came from, and some examples of its idiomatic usage in sentences.
In like Flynn means to be immediately successful or to have achieved acceptance. The idiom in like Flynn carries the connotation of being in a state where one will continue to find success. The expression in like Flynn came into use in the American army in the 1940s, though its origin is murky. Most believe it is somehow tied to the actor Errol Flynn, who always portrayed a successful swashbuckler in his movies. The fact that the word “in” and the name “Flynn” rhyme probably helped to make this phrase popular. Another small faction believes that the “Flynn” in in like Flynn refers to New York political boss Edward J. Flynn, whose candidates never lost. Both theories might be true. Perhaps men from New York entered the army during World War II using a local, colloquial phrase alluding to a political boss, but the phrase was picked up by others with the idea of invoking Errol Flynn.
By ‘good student’ that simply meant if you completed the assigned course work, participated in class (looked awake and alive), and made an effort – you were ‘in like Flynn.’ (The Suburban Times)
Calvert-Lewin is in like Flynn, the first to react to stab in the rebound as Randolph lay supine and his team-mates had a snooze. (The Telegraph)
He wanted to be ‘in Like Flynn,’ but he didn’t want to be ruined for it.” (Los Angeles Magazine)