The coke and mentos inflation is pretty safe, as long as you use an ok amount of coke/mentos. It wouldn’t necessarily kill you but too much can make you sick. I do have a question of my own tho... do mentos work better when cracked or left on its own?
There are virtually no risks with a coke and mentos bloat. It's no more dangerous than drinking soda alone.
And there's a pretty good reason for that.
The physical reaction that takes place when you drop a mentos into a bottle of soda can not take place within the human stomach.
Said reaction, which is called "nucleation", is caused by the pitted shell of the mentos providing a place for bubbles to rapidly form, in the otherwise smooth plastic bottle. Once you've drank the soda, the carbondioxide has already started to separate from the soda. And swallowing a mentos does nothing to hasten that effect.
Any sensation of feeling any more bloated than you would be, from simply drinking soda, is just a placebo.
That said, there is a silver lining here. Since the coke and mentos reaction never creates gas, and only releases what's already there, you never needed mentos anyway. All of that carbon dioxide will still be released into your stomach. And if you can keep yourself from burping it back up, you'll get just as bloated with soda alone as you could have hoped for from a coke and mentos reaction.