Ig Nobels reward research that first makes you laugh and then makes you think. Investigating the internet meme of fluid felines fits the bill – and adds to the physics field of rheology.
Source: Answering the question that won me the Ig Nobel prize: Are cats liquid?
Though it’s not really because cats do fit the container, but more because cats can fit their container,and that because they can relax to a point where you’d swear they were about to flow much as water flows to a lower level.
Though keep in mind that a cat is also able to react to a stimulus at the speed of a, well, cat.