Yep, you've been yawning wrong. Don't worry, Gwynnie has released her personal guide to yawning. She seems to be something of an expert regarding yawning. Read into that what you may.
From what to buy when you're on food stamps, to steaming your lady parts, Gwynnie has been imparting her pearls of wisdom for quite some time via Goop. Here is her latest instalment regarding how to yawn properly... "The other night at a dinner with Michael Lear, a wonderful yogi and important quarterback for mindfulness and meditation in this country, he caught, out of the corner of his very alert eye, the suppression of a yawn...'Please yawn,' he explained.“Really give into it, as it’s the body’s primary way to release and stretch the jaw and neck muscles after a long day of work and conversation.”
As a result, here is Paltrow's step-by-step guide to the process you've been doing since you were in the womb (you weren't "optimising" it then either).
1. Gently tilt your head back to a comfortable position and allow your mouth to hang open widely while you gently extend into it.
2. Contract the back of the throat as if to perform Ujjayi breathing—a whispery breath—which is typically done through your nose with your mouth closed. Breathe deeply through your mouth so you feel the air hit the back of your throat.
3. Inhale and exhale completely while allowing your shoulders to relax as you exhale.
4. When the yawn comes, reach and extend into it, riding the yawn to stretch the jaw muscles.
5. Repeat 8-10 times until tearing starts. As your jaw muscles stretch and relax, and the yawn expands, the lacrimal glands around the eye are squeezed and tearing is induced.
There's also a slightly different technique for YAWN #2 which you can read in your own time here.
The next time you feel like yawning at a dinner party, imagine the delight of the host that you're embracing your body's primal way of releasing "8-10 times until you tear."