You were nowhere around when he did

The Highlander just decapitated me.

....in a video game. Time for a rematch.

Oh dear, I've been caught in a thermonuclear blast.

Luckily the lead kilt that you were wearing saved your life, if not all of your extremities.

Like Kenny from South Park, I just succumbed to a terminal case of boredom.

But it was temporary, South Park reruns saved your life.

I forgot to flash my get out of death card when the tank ran over me.

Luckily, you fit perfectly between the treads and were spared

A Black Hole of Galactic proportions opened up. I was it's epicenter.

Don't talk about your mom that way.

I had one too many cookies and exploded.

They were time-travel cookies. You turned back in time, and decided you should stop eating.

Link did this to me.

Luckily, the cleric had scrolls of stone to flesh and heal for you in her backpack.

I was so exited that I forgot to breathe and suffocated to death.

Fortunately, the reason you forgot to breathe was because you were doing this.

I fell into the sun

You may have fallen in to the sun but for some reason you didn't actually die. At that moment your body reacted and the dormant genes inside of you that you didn't know about awoke to grant you the ability to withstand such an environment without harm.

I carve up my body and remove my organs one by one until I am most definitely dead.