The context is the protagonist works as a forest ranger and he acts on the instrcution of his workmate to tell off some troublemakers, who illegally set off fireworks in the forest. But on his way to the spot he accidentally finds women's underwear and he assumes there are two naked ladies.
-There are two naked ladies out here.
-Can you handle that?
-Come on. I like naked ladies same as anyone. But there's, you know ----
-Two?
-Yeah.
-I know this will be tough for you, but pick your tongue up off the ground and do your job.
Yes, pretty much that. The idea behind the metaphor is that one's tongue hangs out when one is in an excited or eager state.
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zuotengdazuoI guess it means don't get too excited and calm down.Right. I think the comparison is to the behavior of dogs. When they get excited and eager in anticipation that something good is going to happen (e.g., because they're about to be fed or about to be taken on a walk), they start panting hard and their tongues stick out and hang down.