We've all been there - in a yoga class with a teacher that gets right up your nose, whether you're inhaling or exhaling...your nostrils are flaring, your mind is full of the most un-yogic thoughts, I mean really!!! If its a cover teacher, maybe you just won't like any teacher apart from your regular 'guru'. Give the teacher a chance, it may just be different so don't just roll up your yoga mat and flounce out, do your yoga...that means observe your thoughts carefully - why are you getting all stirred up? what are your thoughts telling you about you, your practice, change and expectations? What can you learn from this experience?