[nickpsecurity]

"Pinch your nose, close your mouth, and try to breathe. If you are dreaming, you will be able to inhale and exhale without any conceivable path for the air to flow. Also works if you are underwater."

That has happened to me before! It was more an accident of experimenting around in a lucid dream. I didn't think anything further of it. You're right, though, that it should be a default technique since you can close your mouth and attempt to breath in about any dream situation. Thanks a lot!