Without context, it's difficult to say. It sounds like an insult. What's the rest of the sentence?

I've never heard of this but reading your example you commented to Susan, It sounds like the character was trying to hide his emotions. Trying to present a 'poker face' but the other character could still see that he was disappointed. A stuffed frog would be a dead frog or stuffed animal with no life or emotion so this is why they chose that as a description.