Cats know a lot of weird ways to have fun. Running into the yard to eat grass and then throw it up just happens to be one of them. Fortunately, it isn’t as big a deal for them as it is for us (probably because they never have to clean it up). There’s also substantial evidence that this habit is good for them. Because cats and other carnivores end up eating a lot of indigestible fur, bones and feathers, using fibrous plants like grass to induce vomiting is an effective way to clean out the stomach and keep the intestines safe from blockage and laceration.
Cats who don’t have access to grass will often go after potentially poisonous plants as a substitute. Some common ones include aloe vera, poinsettia and even the rubber plants that people with black thumbs keep around the house. Always make sure houseplants are cat-safe. (source: Animal Planet)