The phrase "little pitcher with big ears" is often used to describe a child who unintentionally overheard something they weren't supposed to, or who is particularly curious and nosy. However, there are several synonyms that could be used in place of this phrase. Some options include "inquisitive child," "eager listener," or "attentive observer." Similarly, one could describe the child as having "keen perception," "acute hearing," or a "nose for gossip." Ultimately, the choice of synonym will depend on the specific context, but there are plenty of alternatives to the oft-used "little pitcher with big ears".