A head which has been clearly narrowed in size (mainly through visual phenomenon) due to the head's owner experiencing an unpleasant surprise, a close call of some sort, long stretches of work or study, or an unacceptable amount of time without food.
Matt had a major skinny head after working 50 hours last week while going to class.
John's car is really giving him a skinny head lately.
That near-accident on the freeway gave Bob a skinny head for the rest of the day.
Working through lunch always gives Eric a skinny head.