What does cat got your tail mean?

"Cat got your tongue" is the correct phrase, not "cat got your tail." It means:

"Why are you not talking? What's wrong?"

The phrase is a playful way of asking someone why they are being silent or unwilling to speak. It suggests that something has surprised or frightened them, making them lose their voice.

It's a common idiom, usually used in a lighthearted way.