I discovered this when the cat was sitting on my chest during an episode of 30 Rock a few months back. I was laughing with my mouth wide open at something marvelous Tina Fey said. This displeased Fluffy so much, she attacked my tongue, bit my shoulder and ran off. Then during an episode of New Adventures of Old Christine she clamped down on my shoulder and wouldn't let go until I pushed her off. Now if there is any movement of my chest other than breathing, the cat will give me a look that says, "Do that again and I'll clamp down on that flesh you call a nose and I'm not letting go this time... At least until you go to the fridge and then I will move beneath your feet meowing incessantly until you feed me." I believe she will do just that so I remove her from my person to sit on the floor. She can't even sit on the same piece of furniture if I'm laughing. She's given me The Look during How I Met Your Mother but I don't laugh at that show like I do the others so it's safe for us to be together.
Yesterday, the cat made her home on my lap, on my arms!, whilst I was typing on Mike's laptop. The constant movement of my arms didn't bother her in the least. The mangy furball didn't flinch- she even started purring!! Thank goodness she doesn't have front claws. God forbid I should laugh.