Lion
"Pleading the Fifth" is a term for invoking the right that allows witnesses to decline to answer questions where the answers might incriminate them, and generally without having to suffer a penalty for asserting the right. (from wiki)
Text of Fifth Amendment to the Constitution:
No person shall be subject, except in cases of impeachment, to more than one punishment or trial for the same offense; nor shall be compelled to be a witness against himself; nor be deprived of life, liberty, or property, without due process of law; nor be obliged to relinquish his property, where it may be necessary for public use, without just compensation....[E]xcept in cases of impeachments, and cases arising in the land or naval forces, or the militia when on actual service, in time of war or public danger...in all crimes punishable with loss of life or member, presentment or indictment by a grand jury shall be an essential preliminary....