A Derp - You're being scared and coughing at the same time. It's like

You're being scared and coughing at the same time. It's like your body is trying to kill you.

I was being chased by a cat and I became a Derp. I was scared and coughing.

I watched a horror movie and I became a Derp. My lungs were screaming.

I got yelled at by my mom and I became a Derp. I was scared and coughing like a dying goat.