(go) tell it/that to the marines!

(go) tell it/that to the marines!

A scornful or incredulous response to a story or statement that one does not believe or finds ridiculous. A: "You know, my dad used to play basketball with the president when they were both kids." B: "Ah, go tell it to the marines! Why do you tell such fibs?" A: "I bet you I could eat 20 hot dogs in less than half an hour!" B: "Tell that to the marines, pal!"
See also: tell, that

tell it to the Marines

Go fool someone else because I won't believe that. For example, He's a millionaire? Tell it to the Marines! This term originated among British sailors, who regarded marines as naive and gullible. [c. 1800]
See also: Marine, tell

Tell it to the marines

A scornful response to an unbelievable story. Beginning in the 17th century, marines were land forces who were stationed on ships of the Royal Navy. As landlubbers, they were understandably naive if not ignorant about life aboard a vessel and on the waves. Sailors took advantage and concocted outlandish stories that the marines swallowed hook, line, and sinker. Accordingly, any outlandish story heard on land or sea and recognized as bilge was greeted with the full rejoinder, “You may tell that to the marines, but the sailors will not believe it,” subsequently shortened over generations to “Aw, tell it to the marines!”
See also: marine, tell