Also, on one's own head. As one's responsibility or fault, as in If the police catch you speeding it's on your own head. This idiom, dating from the 1300s, conjures up the image of blame or guilt falling on someone's head. Also see off one's head.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.