system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are we forced to open our mouth while yawning?
gpt
You can learn to overcome the urge to open your mouth... especially if you are in boring classes or meetings where openly yawning is considered rude! It does require controlling the muscles in the back of your jaw and inner ear area - also very useful for equalising the pressure in your ears while flying or diving...