pitch a line/story/yarn
pitch (one) a line
To tell a lie or only part of the truth in order to convince one of something or to avoid the consequences of something. Don't you dare pitch me a line about being at the library. I want to know exactly where you were tonight. I suspect he's just pitching a line about where all that money came from.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
ˌpitch a ˈline/ˈstory/ˈyarn (to somebody)(informal) tell somebody a story or make an excuse that is not true: He assured me that it really happened, but I reckon he was just pitching me a line.
Farlex Partner Idioms Dictionary © Farlex 2017