when the cat's away (the mice will play):
used to say that people will not behave well when the person who has authority over them is not there
let the cat out of the bag:
to tell someone a secret, especially without intending to
put/set the cat among the pigeons:
to do or say something that causes arguments, trouble etc
look like something the cat dragged/brought in:
to look very dirty or untidy
like a cat on a hot tin roof:
so nervous or anxious that you cannot keep still or keep your attention on one thing
like the cat that ate the canary:
very proud or pleased because of something you have achieved or got
