You can die deep throating a man. To try to answer your own question lie on your back on the kitchen table, lying your head back as far as it will go over the edge and take a 10 inch or larger dildo into your mouth and down your throat as far as you can. Your gag reflex will kick in. Just keep trying. This is a great position for oral sex! Try it!

How far can you get the dildo before you can't breathe anymore? Not far for me. I have to breathe through my nose. If he were to block breathing through my nose, I'd be done for quick. I can't hold my breath very long.

You are unlikely to drown from a man's ejaculate. You might choke to death on it if you're in the position I mentioned above and couldn't breathe through your mouth.