Tell it 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: marine, tell, that

Tell it to the marines!

Inf. I do not believe you (maybe the marines will)! Your excuse is preposterous. Tell it to the marines. I don't care how good you think your reason is. Tell it to the marines!
See also: tell