Don't fancy drinking from one of these.
http://uk.news.yahoo.com/21/20110217/tuk-ancient-britons-used-skulls-as-cups-6323e80.html
http://uk.news.yahoo.com/21/20110217/tuk-ancient-britons-used-skulls-as-cups-6323e80.html
It may have been an act of the utmost repect to "drink in" the knowledge and experience of your former elders, a means of ritually perparing for the hunt / the winter / the birth - etc.