Idioms and Phrases with buy something
Believe something; accept as true or satisfactory. For example, You think he's a millionaire? I just won't buy that. [Slang; 1920s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.