Here's an example.
メイドにはびびった
Who was scared, the speaker, or the maid?
This is context-dependent. It could be the speaker that was frightened, but it could just as easily be the most recent subject (e.g. person) being discussed prior to this sentence. Without more context, it's really impossible to say for certain. In any case, though, someone or something was frightened by the maid.