let the cat out of the bag

bag of bones

A skinny, malnourished person or animal.

bag of tricks

A set of skills, techniques, items of information, or other resources used to help achieve professional or personal goals.

bell the cat

To undertake a dangerous action in the service of a group.

brown bag

A short presentation or seminar on a given subject, especially one given at lunchtime.

buy to let

To purchase a property as in investment, and to let it out for rental instead of living in it

cat and dog life

An unhappy married life marked by arguments and disagreements.

cat got someone's tongue

Why is someone not saying anything?

cat in the meal-tub

Something concealed; a hidden danger.