Idioms and Phrases with i'll say
Absolutely, I strongly agree. For example, Did you enjoy the film?—I'll say. This phrase is generally used alone and for emphasis. [First half of 1900s] For a synonym, see you can say that again.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.