Meaning: To be accepted by the group without question, to have a sure thing.
Example: Don't worry about being accepted as a member at the country club. If you pay the membership fee you will be in like Flynn.
Origin: "In Like Flynn" comes from Errol Flynn's acquittal on statutory rape charges.
Wildly popular, Flynn was a phenomenally successful movie star/sex symbol of the 30's and 40's. His defining role was in "The Adventures of Robin Hood."
Other notable roles include: "Captain Blood", "They Died with Their Boots On", and "The Sun Also Rises."
Flynn was involved in a sensational trial, in which he was accused of having sex with two underage girls on a boat. When Flynn was found not guilty, the phrase "In like Flynn" became a part of the popular vocabulary. The phrase suggests that his acquittal was based on his popularity and celebrity.
The phrase "In Like Flynn" also came to refer to the legendary sexual prowess of Eroll Flynn. Flynn was known to be self indulgent and irreverent. He reportedly had the letters I.G.M.F.Y. on the side of his boat, which stood for "I got mine, F you". When Flynn died, at age 50, he was said to have the body of a 70 year old man.
Thus, if you were sure to get some action, you too were going to be "in like Flynn."
"In Like Flint" is the title of one of the James Bond parody movies starring James Coburn and is an obvious play on the original expression. The other movie in the series was called "Our man Flint". Derek Flint (played by Coburn) was also irresistible to the ladies