The phrase denotes an intense desire or willingness to sacrifice greatly for something. She would give her eye teeth to meet her favorite author.
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Metaphorical
Used metaphorically; no one actually offers their teeth for exchange. I'd give my eye teeth for a vacation in the Bahamas right now.
Pro Tip 3/3
Hyperbolic
It's hyperbole, which means it's an exaggeration to make a point, not to be taken literally. He'd give his eye teeth for a promotion, he's worked so hard.