get the nod - 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.
Receive approval or assent, as in, The contestant got the nod from the judges. Similarly give the nod means “to show approval or assent.” These expressions allude to the quick inclination of the head to indicate approval. [First half of 1900s]