take the starch out of
Deflate or ridicule someone, as in That practical joke at the office party really took the starch out of Nick. This expression, first recorded in 1840, alludes to the starch used to stiffen a shirt.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.