thing or two
Quite a lot, as in You can count on Bob to tell you a thing or two about Iran. This term is nearly always an understatement. [Mid-1800s] Also see under know all the answers.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.