When I was in 7th or 8th grade, I did just that while waiting for first class. I sat opposite a girl in the corridor and was staring right at her crotch, completely zoned out. When I came to, I realized what I was looking at and looked up at her quite angry face. I then, very smoothly I thought, blushed to a tomato red color and faked a zoning out with my gaze in another direction. Crisis averted.