You’re certainly a funny girl for anybody to meet who’s just been up the Amazon for a year.

The line is a piece of character-revealing banter: the speaker frames his own recent isolation (“up the Amazon for a year”) as a benchmark for how strikingly odd or amusing the woman seems on first encounter. It works as a backhanded compliment—“funny” can mean charmingly unconventional, but also socially unexpected—while also advertising the speaker’s worldliness and fatigue with ordinary company. In Sturges’s comic idiom, such a remark typically functions to establish rapid intimacy through wit, turning an improbable personal history into a flirtatious, slightly absurd yardstick for normality.