When someone (by thrusting their hand with two extended fingers into your belly) tries to simulate how it feels when you are all relaxed and comfortable and a kitty suddenly hops up and steps on you, ruining the moment. The two fingers demonstrate (through the use of applied pressure) the tiny paw as the weight from the cat (morbidly obese from domestication) presses down onto the formerly content victim. The result is unease and strong discomfort, borderlining on pain (think chinese water torture but worse).