Doctor: “Yes, what is it I can do for you?”
Blond: “Doctor, yesterday, when I was doing my yoga, one of my friends told me that if I did this particular exercise, all my body’s blood would go into my head. But, when I stand, why doesn’t anyone say that all the blood would go into the legs?”
Doctor: “The fact’s your legs are not that hollow as your head is. “
This joke is included in the Black Book of Jokes. You can order it from here.