bold as brass
Shameless, audacious, impudent. For example, No one had invited her to the wedding, but she showed up at the church, bold as brass. This alliterative simile plays on brass meaning “shamelessness.” [c. 1700]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.