The Dictionary says: "Liquids take the shape of the container while maintaining a constant volume".
We think it is quite clear from these photos: Cats are liquid!

in a cell phone bill

In a tea kettle

In a pretty vase

In a tight space

In a kleenex box

In a baking dish

In a tree stump

In a drinking fountain

In the box of that new gadget you just bought

In a basket

In a shoe box

In another basket

In a box of their medicine

In a tree pot

Between two couch cushions

In a glass

In a tupperware

In a sink

On top of a chair

In a smaller glass

In a car cup holder

On top of some pants

In a tiny basket

In a frying pan

In your favorite baseball cap