Rearrange a bed and its coverings to its condition before it was slept in. For example, Mom taught us all to make the bed before we got dressed. Also see make one's bed and lie in it.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.