Headbanging

Apparently, so I was told today, banging your head against a brick wall will expend 150 calories each hour. Seems a bit low to me although the potential for blood loss after an hour of this activity would surely be quite high. Perhaps it refers to metaphorically bashing your head against a brick wall? If so, then today I have done my body a big favour, and I should really be thanking all those who have helped me in this worthwhile endeavour. However, I think I'll just stick to simmering gently, twitching occasionally, and a large vodka.