Idioms and Phrases with with it, be
with it, be
Also, get with it. Be or become knowledgeable about the current or latest trends, fashions, or ideas, as in She just turned 60, but she's still very much with it, or Get with it, Dad, that kind of razor hasn't been made for years. [Slang; 1920s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.