get it

See catch it.

Understand something, as in He claims his plan is reasonable, but I'm not sure I get it. This synonym for catch on was popularized during the 1980s through a televised political debate in which presidential nominee Ronald Reagan told his opponent, You just don't get it, do you? This particular phrase has since been repeated in numerous contexts where one is expressing exasperation at someone's failure to understand something. The phrase is also put in the past tense, got it, meaning “understood.” For example, We're leaving tomorrow.—OK, got it. [Colloquial; late 1800s] Also see get the message.