I shit you not

When you say something unbelievable but true.

The expression means I am being honest.

A phrase typically, but not always, used in conversation; can also be used in response to a fact, or its opposite, in media; the appropriate response to any sentence including any variation of the descriptor 'bullshit', when the word 'shit' is being used as a verb, and the preceding perceived assertion or premise reflects a known truth or fact. Also used as its reverse as a prank, to generate belief in something patently false and normally unbelievable.

When some one tells the truth about something usually unbeleivable.

used to state that a story is 100% true, no matter now insane, silly, or crazy it sounds, "one cent" is the part stating that not even 1% of this story is fake

A horribly translated version of something nobody even gives a shit about.

used to describe the wildest part of a story is 101% true, no matter how insane it might seem