"i claim the 5th." "i decline to testify on the basis of my fifth amendment right! " “i’d like to plead the fifth! (explains the meanings of this statement.)

No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation

Meaning that the person can not be held capiable of anything untill there is evinced 

The Fifth Amendment of the U.S. Constitution prevents government officials from abusing authority is such a way that forces a citizen to comply with answering questions or speak their mind in an potentially incriminating manner during legal proceedings. Basically, "pleading the fifth" calls for the "right to remain silent" in terms of the law. An individual does not have to answer to an authority's questioning if they choose not to.

I'm pretty sure that's called a volcano