Meaning of "The small-time hussy speaks the lingo of eternity—do me a favor!"?

Hello everyone. I am reading a novel, and I came across this expression. Could you please let me know its meaning?

Just don’t fall in love with me. Which is when she planted a kiss under my ear—You smell good, uttered almost like a jeer and an afterthought. Venom, venom, venom. Venom and its antidote, like the warm, puffed taste of newly baked bread on a cold morning when the crust suddenly cuts into your gum and turns the most wholesome taste on earth into rank and fulsome gunk. No things, okay? meaning, No sullen faces, no sulky-pouties, no guilt stuff, okay? Because it could turn into her hell. Get real, Schwester! The mopey heiress from Maine didn’t rattle so many keys before unlocking the fortress. The small-time hussy speaks the lingo of eternity—do me a favor! And all that talk of lying low—what prattle and claptrap!

- André Aciman, Eight White Nights, Second Night

This is a novel published in the United States of America in 2010. This novel is narrated by the nameless male protagonist who meets Clara at a Christmas party in Manhattan. Now the protagonist is thinking how Clara would warn him not to fall in love with her.

In this part, I wonder what the underlined expression means.

As for "eternity," I am vaguely guessing that she might be referring to the poem bearing the title of "I saw Eternity the other night" which appeared in the previous chapter. But I am not sure about the nuance of the sentence, and what "do me a favor" might mean. Also, I wonder what "the small-time hussy" speaking "the lingo of eternity" might mean. o_O Thank you very much for your help.