lose one's shirt - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Face financial ruin, go bankrupt, as in He lost his shirt in the last recession. This expression implies one has lost even one's shirt. [Early 1900s]