cat got one’s tongue: Can’t speak because of shyness, surprise, etc.
What’s the matter – cat got your tongue? I asked you what you did with the car keys! Don’t tell me you lost them!cat nap: A short nap taken during the day. This idiom comes from the observation that cats tend to take frequent, brief naps throughout the day, and are easily awakened.
The security guard was fired for catnapping on the job.