it happens to people. yeah, it can be a mood killer indeed, bummer.
well, if you ever do yawn again, just know that its because you're not breatheing properly and your body subconciously makes you inhale a huge amount of air, lol. it sounds weird, but its sort of true
i've been with a girl that was falling asleep, so i just started thrusting faster, can't sleep if your body is shaking, right? hehe