It is incredibly uncomfortible to consume both at the same time. It produces more gas that gives you a stomach ache. But it usually goes away in a few
minutes or until you burp.
Know what's fun? Put a whole bunch of pop rocks in your mouth then add some coke. Don't swallow. See how long you can keep them in. Good party game.
I've done this a ton of times. I'm pretty sure I'm not dead, but hey I could be wrong. It's actually pretty amusing, and all it causes is burping.
I suggest you try it.
No this doesn't kill you but since this is just a urban legend, you can have fun with it. You can consume them in front of unsuspecting people or
even kids at a family bbq, or something like that and pretend like it is making your insides explode.